Study finds less-aggressive chemotherapy after initial treatment for metastatic colorectal cancer to be more beneficial

December 19, 2019

PHOENIX -- A Mayo Clinic study involving 5,540 patients with metastatic colorectal cancer finds that maintenance chemotherapy after initial treatment is more beneficial for patients whose disease is under control, compared with more aggressive treatment.

A maintenance strategy with a fluoropyrimidine chemotherapy, such as 5-FU or capecitabine, is preferred, though observation with no chemotherapy is an acceptable option for some patients, according to the analysis of results from 12 randomized clinical trials. The study appears in JAMA Oncology.

"Based on these findings, switching to a lighter, maintenance regimen of chemotherapy or even taking a break in treatment for some patients is appropriate, with reintroduction of full chemotherapy when the disease progresses," says Mohamad Sonbol, M.D., a Mayo Clinic oncologist.

"The goal of therapy in metastatic colorectal cancer is to prolong life while preserving or improving quality of life. As most of these therapies are associated with side effects, it's important to use treatments that achieve a maximum benefit with the fewest side effects," says Dr. Sonbol, the study's first author.

Colorectal cancer is the third most common cancer in the U.S. At diagnosis, 1 in 4 patients will have cancer that already has spread to other organs. Randomized controlled trials have tested different strategies for continuing chemotherapy after initial treatment, compared with less-intensive maintenance chemotherapy and observation without chemotherapy.

The results of these trials have been inconsistent, making it challenging to draw conclusions. The Mayo Clinic study used a network meta-analysis of findings from the 12 trials to compare the treatment strategies used and the outcomes.

The analysis showed no benefit in continuing full chemotherapy until progression of the disease, compared to the other strategies. Also, all maintenance strategies showed significant improvement in disease control -- progression-free survival -- compared with observation. The investigators further compared different maintenance treatments used and found that the preferred regimen is fluoropyrimidine with or without the addition of bevacizumab, a medication used in combination with cancer-fighting drugs.

"Many chemotherapies that are used are initially beneficial in both shrinking and controlling the cancer," says Tanios Bekaii-Saab, M.D., a Mayo Clinic gastrointestinal oncologist and the study's senior author. "However, after a few months of therapy, the maximum benefit is usually achieved and the main focus should be on how to continue that benefit while minimizing side effects. This study confirms that switching to maintenance treatment is appropriate and beneficial, with introduction of full chemotherapy later upon progression of the disease."
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