It all sounds similar to a dance event - but are singles or couples dancing here? This was the question Ali Isbilir and Dr. Paolo Annibale at the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC) were trying to answer. However, their investigation did not involve a ballroom, but the cell membrane. The question behind their investigation: does a particular protein receptor on the surface of cancer and immune cells appear alone or connect in pairs?

The receptor is called "CXCR4" - the subject of heated debate among experts in recent years due to its mysterious relationship status. Does it appear in singles or pairs on the cell membrane? And what makes the difference? The research team of the Receptor Signaling Lab at the MDC, has now solved the puzzle of its relationship status for the first time. Their findings were recently published in the journal "Proceedings of the National Academy of Sciences" (PNAS).

CXCR4 is an important receptor on immune and cancer cells
"When CXCR4 is found in large numbers on cancer cells, it also ensures that they can migrate, thereby laying the foundation for metastases," says lead author Isbilir. Metastases are known to be difficult to treat; some patients die as a result of these secondary tumors.

CXCR4 is also involved in inflammations. The center of inflammation releases messenger substances from the chemokine class. In lymph nodes, chemokines ensure that immune cells form many CXCR4 receptors on their membrane. With the help of these receptors, immune cells can locate the center of inflammation and migrate to it. The name CXCR, which stands for "chemokine receptor," also refers to this ability. "Such receptors are the most important target structures in pharmaceutical research," emphasizes Professor Martin Lohse, the last author of the study. "Approximately one-third of all drugs address this class of receptors."

Whether such receptors are present as pairs or singles is therefore not only central to basic research, but also to the pharmaceutical industry. Using new methods of optical microscopy, the team has now been able to answer this question for the first time. Apparently, CXCR4 wants to remain noncommittal - it occurs temporarily in pairs (as a transient dimer), but also alone (as a monomer). The team found that the relationship status depends largely on how many CXCR4 receptors are located on a cell. If the cell surface is densely occupied, more pairs are formed. If only a few receptors are present, they more often appear singly. At the same time, the researchers could show that certain drugs acting as CXCR4 blockers can suppress pair formation. "It is assumed that CXCR4 pairs negatively affect one's health. We can use our new microscopic methods to test whether this is really the case," explains Lohse.

Fluorescent pairs and singles
The scientists combined two recent optical microscopy methods: Using single-molecule microscopy, they were then able to determine the relationship status of individual CXCR4 receptors on the surface of living cells. Fluorescence fluctuation spectroscopy also made it possible to measure the relationship status in cells that had a large number of receptors. The special feature here: to do this, the researchers had to develop a method to efficiently mark all receptors. They also had to develop a highly sensitive microscopy strategy with which they could see individual molecules and their oligomerization. 

"The exciting thing is that we can now use these fluorescence methods to study living cancer cells. We can find out whether CXCR4 is present in pairs or alone," says Annibale, who is co-head of the Receptor Signaling Lab. "And then we can apply CXCR4 blockers to singles and pairs and test which are more effective against tumors. This will hopefully lead to more specific cancer drugs with fewer side effects."
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Pathologists today are also examining the properties of patients' cancer cells in detail. This allows cancer therapies to be designed in the most personalized and effective way possible. Annibale hopes that the approach could be now used for screening the effects of different drugs on the function of this and similar receptors. This could be helpful in devising new therapies for breast, or lung cancer, for example.

Işbilir et al. Advanced fluorescence microscopy reveals disruption of dynamic CXCR4 dimerization by subpocket-specific inverse agonists. PNAS November 17, 2020 117 (46) 29144-29154; https://doi.org/10.1073/pnas.2013319117 [Article]
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Researchers find that the phenomenon of chromothripsis results in rearranged genomes and extra-chromosomal DNA that helps mutated cells not only evade treatment, but become more aggressive.

Cancer is one of the world's greatest health afflictions because, unlike some diseases, it is a moving target, constantly evolving to evade and resist treatment.

In a paper published in Nature, researchers at University of California San Diego School of Medicine and the UC San Diego branch of the Ludwig Institute for Cancer Research, with colleagues in New York and the United Kingdom, describe how a phenomenon known as "chromothripsis" breaks up chromosomes, which then reassemble in ways that ultimately promote cancer cell growth.

Chromothripsis is a catastrophic mutational event in a cell's history that involves massive rearrangement of its genome, as opposed to a gradual acquisition of rearrangements and mutations over time. Genomic rearrangement is a key characteristic of many cancers, allowing mutated cells to grow or grow faster, unaffected by anti-cancer therapies.

"These rearrangements can occur in a single step," said first author Ofer Shoshani, PhD, a postdoctoral fellow in the lab of the paper's co-senior author Don Cleveland, PhD, professor of medicine, neurosciences and cellular and molecular medicine at UC San Diego School of Medicine.
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"During chromothripsis, a chromosome in a cell is shattered into many pieces, hundreds in some cases, followed by reassembly in a shuffled order. Some pieces get lost while others persist as extra-chromosomal DNA (ecDNA). Some of these ecDNA elements promote cancer cell growth and form minute-sized chromosomes called 'double minutes.'"

Research published last year by scientists at the UC San Diego branch of the Ludwig Institute for Cancer Research found that up to half of all cancer cells in many types of cancers contain ecDNA carrying cancer-promoting genes.

In the latest study, Cleveland, Shoshani and colleagues employed direct visualization of chromosome structure to identify the steps in gene amplification and the mechanism underlying resistance to methotrexate, one of the earliest chemotherapy drugs and still widely used.

In collaboration with co-senior author Peter J. Campbell, PhD, head of cancer, aging and somatic mutation at Wellcome Sanger Institute in the United Kingdom, the team sequenced the entire genomes of cells developing drug resistance, revealing that chromosome shattering jump-starts formation of ecDNA-carrying genes that confer anti-cancer therapy resistance.

The scientists also identified how chromothripsis drives ecDNA formation after gene amplification inside a chromosome.

"Chromothripsis converts intra-chromosomal amplifications (internal) into extra-chromosomal (external) amplifications and that amplified ecDNA can then reintegrate into chromosomal locations in response to DNA damage from chemotherapy or radiotherapy," said Shoshani. "The new work highlights the role of chromothripsis at all critical stages in the life cycle of amplified DNA in cancer cells, explaining how cancer cells can become more aggressive or drug-resistant."

Said Cleveland: "Our identifications of repetitive DNA shattering as a driver of anti-cancer drug resistance and of DNA repair pathways necessary for reassembling the shattered chromosomal pieces has enabled rational design of combination drug therapies to prevent development of drug resistance in cancer patients, thereby improving their outcome."
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The findings address one of the so-called nine Grand Challenges for cancer therapy development, a joint partnership between the National Cancer Institute in the United States and Cancer Research UK, the world's largest independent cancer research and awareness charity.

Shoshani et al. Chromothripsis drives the evolution of gene amplification in cancer. Nature. 2020 doi: 10.1038/s41586-020-03064-z [Abstract]

A new and less invasive treatment developed by Cancer Research UK researchers is safer than standard major surgery for early-stage rectal cancer, giving patients a better quality of life with fewer life-altering side effects, results from a pilot study show.

Results from the TREC trial show that a combination of local keyhole surgery and radiotherapy, rather than major surgery that removes the whole rectum, prevents debilitating side effects, such as diarrhoea, or the need for a permanent colostomy bag.

Patients reported a better quality of life with the new treatment, with less impact on their family and social life, and felt more positive about their body image and the way their bowels work.

Every year, 11,500 people in the UK are diagnosed with a tumour located in the rectum, the last part of the intestine which connects to the anus. Standard treatment is a major operation to remove the whole rectum, even if the cancer is early stage. About 25% of these major surgeries are done on small, early-stage tumours, and while it is effective, the operation can lead to long-term side-effects that seriously impacts quality of life for survivors.

43% of rectal cancers are caught at an early stage (stage 1 and 2) and doctors need better, less invasive treatments for these tumours.

Mr Simon Bach and his team at the University of Birmingham, along with collaborators at the University of Leeds, have developed a new treatment approach called 'organ preservation' for early-stage rectal cancer that uses radiotherapy followed by local keyhole surgery 8-10 weeks later to remove only the part of the rectum affected by cancer.

Mr Simon Bach, lead researcher, says: "We took a lot of inspiration from progress against breast cancer. In the early 90s, most people with breast cancer would have a mastectomy, where the whole breast is removed, as the first part of their treatment. But now, due to awareness campaigns, the breast screening programme and new treatments, mastectomy is much rarer. We wanted to test a similar approach for our rectal cancer patients."

To test whether organ preservation treatment could be a suitable alternative to major surgery for early-stage rectal cancer, 123 patients were enrolled in the TREC trial.

Doctors gave the new treatment to 61 patients for whom the major surgery would have been considered unsafe.

In addition, 55 patients were randomised to two treatment approaches; 28 received major surgery and 27 received the new organ preserving treatment. 70% (19/27) of these were treated successfully, meaning their tumour was removed while preserving the rest of their rectum and their cancer did not return during the 3- to 5-year follow-up period. People who received the new treatment also reported fewer side-effects than people who had major surgery.

The analysis of patient-reported quality of life for 3 years after treatment, by Cancer Research UK clinical trial fellow Dr Alexandra Gilbert, found that people who received the new treatment fared better. They reported less diarrhoea, less embarrassment about their bowel functions, felt more satisfied with their body image, and felt like their treatment interfered less with their family life and social life compared with those who received major surgery.

Similar results were also seen in the 61 patients for whom the standard surgery would have been considered unsafe, showing that the new treatment could be a safe and effective option.

Co-author Dr Alexandra Gilbert, from the University of Leeds and Leeds Teaching Hospitals NHS Trust, said: "When talking about cancer treatment, the focus is rarely on how severe the effects can be for patients. But we studied this in detail and found that our organ preservation approach made a significant difference to people's quality of life. One of the most striking benefits was avoiding the need for a stoma bag, which we know is really important to our patients."

Mr Simon Bach and his team are now running an international, larger-scale version of their study, called STAR TREC, across the UK, Netherlands and Denmark. The trial will help decide whether the new treatment should become the new standard treatment for early rectal cancer. This follow-up trial is currently open for recruitment, and importantly, patients may decide if they prefer to receive organ preservation.

The researchers are encouraging people who have been diagnosed with an early-stage rectal tumour to discuss their options with their surgeon should they wish to consider joining the ongoing trial.

Michelle Mitchell, chief executive of Cancer Research UK, said: "When people with cancer finish their cancer therapy, it's not the end of the ordeal. The physical and emotional strain from the effects of treatment can last for years afterwards, or even a lifetime."

"Patients are at the heart of what we do, and that's why results from trials like TREC are such good news. If we can find less intensive treatments with fewer side-effects, patients feel stronger and more confident, and they are in a better place to socialise, enjoy time with their friends and family, and live life to the fullest."

Martin Ledwick, Cancer Research UK's head information nurse, said: "This new treatment could be life-changing for people diagnosed with early-stage cancer. Diagnosing bowel cancer earlier means treatments are far more likely to work, so we encourage eligible people to consider taking part in bowel cancer screening when they receive their testing kit, and for anyone who notices any changes to their body to tell their GP about it."

Bach et al. Radical surgery versus organ preservation via short-course radiotherapy followed by transanal endoscopic microsurgery for early-stage rectal cancer (TREC): a randomised, open-label feasibility study. 2020, DOI:https://doi.org/10.1016/S2468-1253(20)30333-2 [Article]

The risk of serious adverse effects on the blood status and bone marrow of patients during chemotherapy can be predicted by a model developed at Linköping University, Sweden. This research may make it possible to use genetic analysis to identify patients with a high probability of side effects. 

It is often difficult during cancer treatment to achieve a balance between getting rid of as many tumour cells as possible, while at the same time not causing serious side effects.

One of the common properties of tumour cells is that they grow rapidly and in an uncontrolled manner. The chemotherapy drugs that are used to treat cancer have for this reason been designed to kill rapidly growing cells. But the treatment also kills normal cells that grow rapidly. One of the more sensitive tissues is the bone marrow, where various types of blood cell are formed at a rapid rate. Approximately 25% of lung cancer patients who receive combination treatment with the drugs gemcitabine and carboplatin experience life-threatening side effects on the bone marrow during standard treatment. In many cases, the treatment must be discontinued.

We know that genetic factors play a role in the response of an individual to these treatments. Complicated interactions between many genes are probably involved. The scientists who carried out the study have therefore investigated whether genetic signatures exist that can be used to identify the patients at a high risk of experiencing severe side effects from the treatment. This would enable them to adapt treatment to the individual more accurately from the start: those with a low risk of side effects can be given higher doses, with a stronger effect on the cancer, while those with highest risk can be given another treatment. 
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The study, published in npj Systems Biology and Applications, is a collaboration between researchers in pharmacogenetics and bioinformatics. They determined the complete DNA sequences of 96 patients with non-small cell lung cancer who had been treated with gemcitabine/carboplatin. Sequencing of the whole genome in this way provides information about millions of genetic variants that may be interesting. The researchers wanted to see whether they could find in this huge amount of data functional groups of genes that were linked to the degree of toxicity that the treatment had had on the bone marrow of the different patients

The researchers in a first step identified a network of 215 genes that were tightly linked to each other. This network was particularly rich in genes that have been associated with these drugs in previous studies. The next step was to reduce the number of genetic variants in the gene network to the 62 that are included in the final model. The researchers demonstrate that the model can be used to classify patients into one of two groups, with high or low probability of experiencing severe side effects.

"It's extremely interesting that the genes involved are associated with cell division, in particular in bone marrow. We managed not only to predict side effects for the patients, but also show that the model is biologically relevant", says Henrik Gréen, professor at the Department of Biomedical and Clinical Sciences, Linköping University.

The prediction model must be tested in further studies before it can be used in the clinic. Increasingly advanced methods of genetic analysis are being introduced into the Swedish medical care system, which makes it possible in the long term to introduce this type of method, built on an analysis of many genes at the same time.
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"We want to work towards establishing a standard within translational bioinformatics, and show that the same type of method can be applied in several medical situations. The patient material here may appear to be small, but we have even so demonstrated that this approach can be used to predict the severity of side effects for patients", says Mika Gustafsson, senior lecturer in the Department of Physics, Chemistry and Biology at Linköping University, and, together with Henrik Gréen, leader of the study.

Björn et al. Whole-genome sequencing and gene network modules predict gemcitabine/carboplatin-induced myelosuppression in non-small cell lung cancer patients. NPJ Syst Biol Appl. 2020;6:25. doi: 10.1038/s41540-020-00146-6 [Article]

A teaching and research hospital like the University of Colorado can lead the way in improving the care of underserved communities.

"Like many other tertiary care centers, we have a great number of clinical trials, but not everyone who could benefit from them enjoys access," says Karam. "We need to enhance our ability to deliver more broadly the best and newest trials that can extend life and decrease symptom burden."

Black lives matter
The disparities that Black community members face are gaining national attention after the deaths of George Floyd and other Black men and women. But one area of inequity that has not received as much attention is access to medical care. Last month, dozens of providers gathered at the Anschutz Medical Campus to support a national movement by kneeling with fellow White Coats for Black Lives members.

"Speaking up is an important first step towards change," says Karam. "But it must be accompanied by policy change aimed at expanding access to care. We invest billions in new therapies that might or might not work but devote far less attention to helping our socially challenged patients get through the door, which our study shows does work."

The doctors say that more work is needed to overcome hurdles to health care access.
"We also need to educate the next generation of doctors on showing compassion and sensitivity to issues of race, income, social challenges, addiction, and other access barriers," says Karam.

What the CU Cancer Center is doing to help
Prior to this study's publication, Dr. McDermott was awarded a grant from the CU Cancer Center Office of Community Outreach and Engagement to increase the representation of the Hispanic populations in head and neck cancer clinical trials. Colorado has a large population of Hispanics, which makes that population an easier place to begin making changes.

"Our goal is to use that project to branch out to Hispanics, Blacks, and anyone else with socioeconomic issues that currently compromise their access to care," says McDermott.

The CU Cancer Center will continue studying the health disparities for different types of cancer and investigating strategies for eliminating the barriers faced by those needing care.

McDermott et al. Elderly Black Non-Hispanic Patients With Head and Neck Squamous Cell Cancer Have the Worst Survival Outcomes. J Natl Compr Canc Netw. 2020 doi: 10.6004/jnccn.2020.7607 [Article]

Researchers followed the women for an average of 52 months to see whether any of them developed cardiovascular disease. In women with no calcifications (a score of zero), 5% went on to be hospitalised or to die from cardiovascular disease. In women with a score of between one and ten, 8.9% were hospitalised with or died from cardiovascular disease. In women with a score of 11-100, the figure was 13.5%, in women with a score of 101-400 it was 17.5% and in women with a score above 400, it was 28.3%.

When researchers took into account women's ages and the year they were diagnosed, they found a 3.7 times greater risk of cardiovascular disease in women with the highest score (above 400), compared with women with no calcifications. In women who were treated with a particular type of chemotherapy called an anthracycline, the association between high CAC score and cardiovascular risk was even stronger.
The researchers acknowledge that they were unable to take other cardiovascular disease risk factors, such as smoking, high blood pressure and diabetes, into account in this study, although these are factors they are looking at in another study.

Professor Verkooijen said: "We believe this is the first time anyone has conducted a large-scale study like this. We've shown that we can use routine CT scans to indicate which breast cancer patients are most likely to develop cardiovascular disease. Now we need to do more research to find out what can be done to help minimise this risk, for instance whether patients' cardiovascular health should be monitored or treated."

The researchers are now working to get their technique for predicting cardiovascular disease risk into use in several radiotherapy units in The Netherlands. Patients taking part in this study who are found have an increased risk will be offered further cardiovascular screening and lifestyle advice, and their CAC score will be used in planning their breast cancer treatment.

Professor Nadia Harbeck, from the University of Munich (LMU) in Germany, is chair of the 12th European Breast Cancer Conference and was not involved with the research. She said: "Our key aim is treating breast cancer effectively. However, it's just as important that we don't over-treat patients because cancer therapies can have serious and long-term side-effects.
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"This is a clever study because it shows us how the CT scans we are already taking can also be used to discover which women have the highest risk of cardiovascular disease. We look forward to further results from these researchers and hope they might show us how best to help women who are at a higher risk of cardiovascular disease."

European Breast Cancer Conference (EBCC-12) - virtual

Is increased coffee consumption associated with improved survival in patients with advanced or metastatic colorectal cancer?

In a study of 1171 patients with advanced or metastatic colorectal cancer, increased coffee consumption  was associated with lower risk of disease progression and death. Significant associations were noted for both caffeinated and decaffeinated coffee.

Among patients with advanced or metastatic colorectal cancer, the study found that increased coffee intake was associated with lower risk of disease progression and death.

Mackintosh et al. Association of Coffee Intake With Survival in Patients With Advanced or Metastatic Colorectal Cancer. JAMA Oncol, 2020. doi:10.1001/jamaoncol.2020.3938 [Article]

As a graduate student in the lab of Robert Doebele, MD, PhD, at the University of Colorado, Denver, Vaishnavi was the lead author on the discovery of the involvement of NTRK1 fusions in lung cancer. That work led to the rapid testing and approval of drugs called TRKA inhibitors in the clinic. These drugs were the first ever "agnostic" agents approved by the US Food and Drug Administration, meaning the drugs were approved for any patient with a type of cancer that carried the NTRK1 abnormality. Vaishnavi's background studying these molecules in lung cancer was essential to the current pancreas cancer project.

​To better understand cancers that carry this abnormality, McMahon, Vaishnavi, and Conan Kinsey, MD, PhD, a physician-scientist at HCI and assistant professor of internal medicine at the U of U with expertise in pancreatic cancer biology, developed mouse models for both pancreas cancer and lung cancer driven by the NTRK1 abnormality. "The lung and pancreas are two clearly distinct organs with unique features that shape the development of solid tumors," says Vaishnavi. "It is important to study how cancers begin and operate in the correct tissue context and microenvironment."

In this study, McMahon and his colleagues evaluated rational drug combinations that greatly enhanced the durability of tumor response and prevented the onset of lethal drug resistance in the mouse models. Their hope now is for this laboratory research to progress toward clinical trials in patients, and, ultimately, to improve treatment options for patients affected by these aggressive cancers.

Vaishnavi et al. Inhibition of MEK1/2 Forestalls the Onset of Acquired Resistance to Entrectinib in Multiple Models of NTRK1-Driven Cancer, 2020, https://doi.org/10.1016/j.celrep.2020.107994 [Article]

​​Study Details
Past studies had established that having breast cancer increases risk of developing heart disease, due largely to the wear and tear caused by chemotherapy and radiation. While searching the literature, the current team was surprised to find that no lab had yet examined whether heart attacks in turn worsen cancer progression.

To examine the mechanisms behind this link, the authors created a model wherein mice had cancer cells implanted in their breast tissue, and then underwent the surgical closure (ligation) of their left anterior descending coronary artery. The human counterpart of this artery is a common site of blood flow blockage that causes a heart attack, also called myocardial infarction or MI, often triggered by cholesterol deposits or "hardening of the arteries."

The research team then compared cancer growth in mice with and without the ligation, with the non-ligated mice undergoing a sham surgery to account for changes caused by the surgery itself. While the exact biochemical signal responsible has yet to determined, the study found that the heart attack causes system-wide changes to immune cells in bone marrow, the bloodstream, and in tumors.

Firstly, the researchers found that mice with ligation came with a "marked increase" in the number of cells in tumors with surface markers that indicated they were quickly multiplying (Ki67+ cells), a measure of aggressive growth.

Experiments in mice also linked an induced heart attack to a 30 percent increase in the number of white blood cells called monocytes. Such cells are known arise and mature in bone marrow, enter the blood stream, and home in on sites of injury, infection, and abnormalities like tumors.

Furthermore, the authors found that after a heart attack, there was a 60 percent increase in the proportion of immature monocytes in tumors programmed to no longer attack cancer cells there.

Still other tests revealed that heart attack changed the action of 235 genes expressed in these immune cells in mice, many of which would otherwise amplify immune attack. Other important MI-driven changes occurred, not in the gene code, but instead in the protein superstructure that houses the DNA code, making genetic instructions that amplify immune responses less accessible to the machinery meant to read them.

"Given the evidence of cross-talk between cardiovascular disease and breast cancer, measures that lower the risk for a cardiovascular event, such as exercise and treating high cholesterol and high blood pressure, warrant further study as potential ways to keep patients' cancer from getting worse," says first study author Graeme Koelwyn, PhD, who led the study in Moore's lab.

Koelwyn et al. Myocardial infarction accelerates breast cancer via innate immune reprogramming. Nat Med (2020). https://doi.org/10.1038/s41591-020-0964-7 [Abstract]

Patients who already used opioids, sedatives or antidepressants prior to colorectal surgery may experience significantly more complications post-surgery.  The study examined 1,201 patients 18 years of age and older who underwent colorectal resection for any indication other than trauma at UK HealthCare. Of these patients, roughly 30% used opioids, 28% used antidepressants and 18% used sedatives, all legally prescribed by a doctor pre-operatively.

Patients on any of these medications showed an increase in several common complications post-surgery, including infections, prolonged intubation, longer length of stay, readmissions, respiratory failure and even mortality. These problems were particularly pronounced in patients who regularly used opioids prior to surgery.

The preoperative use of opioids, sedatives and antidepressants is on the rise in the U.S. Though the current opioid crisis has raised awareness for limiting opioid use, many patients still receive opioids for pain management, and finding the right balance of medication is an ongoing issue for many patients and doctors. Patients with anxiety disorders or other mental health issues often receive sedatives or antidepressants.

However, risk prediction models for postoperative complications do not take these common medications into consideration, says Dr. Avinash Bhakta colorectal surgeon at the UK Markey Cancer Center and lead author on the study. To reduce complications post-surgery, he says more needs to be done to help patients reduce their need for these drugs in managing pain and anxiety prior to any major surgery.

"Most colorectal resections are elective in nature, so we want to focus on the use of opioids and sedatives and counsel patients on the need to decrease the use of these drugs before surgery," Bhakta said. "These drugs are necessary for many patients, but if we can decrease how much they're using, we can help decrease long-term complications. Not only do we want to improve their surgical outcomes, we want to improve their overall health."

Gan et al. A Retrospective Review: Patient-Reported Preoperative Prescription Opioid, Sedative, or Antidepressant Use Is Associated With Worse Outcomes in Colorectal Surgery. Dis Colon Rectum. 2020;63:965-973. doi: 10.1097/DCR.0000000000001655 [Article]