Rectal cancer is cancer in the last several inches of the large intestine. About 45,000 people in the U.S. are diagnosed each year. Standard treatment often combines chemotherapy, radiation, and surgery, but the sequence and intensity depend on how far the cancer has spread and where exactly in the rectum it sits.
What's actually going on in research
Trials are testing whether some people can avoid surgery entirely through radiation and chemotherapy alone, especially for tumors that disappear completely. Immunotherapy drugs like pembrolizumab now work well for the 5-15% of rectal cancers with mismatch repair deficiency. Researchers are also studying shorter radiation courses, targeted drugs for specific mutations, and ways to preserve the rectum and sphincter function.
Watch-and-wait approaches
Some people whose tumors disappear after chemotherapy and radiation now skip surgery and are monitored closely instead. Studies are refining which patients are good candidates and how to follow them safely.
Immunotherapy for MSI-high tumors
Pembrolizumab and dostarlimab can shrink or eliminate tumors with mismatch repair deficiency, sometimes before surgery is needed. Trials are testing whether immunotherapy alone, without chemotherapy or radiation, can control these cancers.
Organ preservation
New radiation techniques and drug combinations aim to destroy tumors while keeping the rectum intact. Trials are studying how to select patients who can avoid a permanent colostomy.
What to know before you search
Eligibility depends on tumor stage, location in the rectum, genetic features like MSI or MMR status, prior treatments, and whether the goal is organ preservation or cure.
What types of trials are currently open
- Treatment trials — Testing new chemotherapy combinations, targeted drugs for specific mutations like BRAF or HER2, or immunotherapy drugs for tumors with certain genetic features.
- Watch-and-wait trials — Studies of surveillance instead of surgery for people whose tumors disappear completely after initial treatment.
- Radiation trials — Testing shorter or more targeted radiation schedules, or combining radiation with new drugs to shrink tumors before surgery.
- Surgical trials — Comparing different surgical approaches, including organ-preserving techniques and less invasive procedures.
- Prevention trials — Studies of screening methods and risk-reduction strategies for people with family history or genetic predisposition.
Recently added Rectal Cancer trials
Aerobic Exercise and Guided Imagery in Low Anterior Resection Syndrome
Low Anterior Resection Syndrome (LARS) is a common complication after sphincter-preserving rectal cancer surgery and may negatively affect bowel function and quality of life. Although exercise has been shown to improve physical function and well-being in cancer survivors, evidence regarding its effects on LARS symptoms remains limited. This randomized controlled, multicenter study aims to evaluate the effects of an aerobic exercise program combined with guided imagery on bowel symptoms, quality of life, physical activity level, functional capacity, and psychological well-being in patients with LARS after rectal cancer surgery. Participants will be randomly assigned to either an intervention group receiving aerobic exercise and guided imagery in addition to standard care or a control group receiving standard care alone. Outcomes will be assessed at baseline and after the intervention period using validated clinical and patient-reported outcome measures. The findings of this study may contribute to the development of evidence-based rehabilitation strategies for improving bowel function and quality of life in patients with LARS following rectal cancer surgery.
Hyperpolarized 13C-MRI and Radiomics in Rectal Cancer
This study is testing new imaging and analysis methods to improve how doctors predict treatment response in rectal cancer patients receiving chemoradiotherapy. Current MRI scans sometimes miss complete tumor response, which can lead to unnecessary surgery. To address this, researchers will use a special MRI technique called hyperpolarized carbon-13 MRI, along with blood and tissue analysis (metabolomics) and advanced image feature analysis (radiomics). These tools can track how cancer cells use energy and how metabolism changes during treatment. The study will follow 30 rectal cancer patients at Chang Gung Memorial Hospital over 3 years. Patients will undergo standard MRI, colonoscopy, and advanced metabolic imaging before and after treatment. Results will compare patients whose tumors completely respond to therapy with those who do not. The goal is to see if metabolic changes detected by hyperpolarized MRI and metabolomics can predict treatment outcomes earlier and more accurately. This may help doctors avoid unnecessary surgery and provide more personalized care for rectal cancer patients.
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