Carla K. Johnson, Associated Press
Cancer patients can safely omit certain chemotherapy or radiotherapy after surgery, two new studies (including a Canadian study) that looked at shorter, gentler cancer treatments show.
Researchers are trying to identify patients who can go without unnecessary treatments to reduce side effects and unwanted costs.
A new study used a blood test to identify colon cancer patients who might skip chemotherapy after surgery. Another suggests that patients with low-risk breast cancer may not need radiation therapy after lumpectomy.
The studies were discussed at the annual meeting of the American Society of Clinical Oncology, which concluded Tuesday in Chicago. The colon cancer study was funded by the Australian and US governments, and by non-profit groups. It was published Saturday in the New England Journal of Medicine.
Dr. Stacey Cohen of the Fred Hutchinson Cancer Center in Seattle, who reviewed the colon cancer study and was not involved in the work, explained it.
Many colon cancer patients receive chemotherapy after surgery, even though they may be cured. Treatment can be accompanied by side effects such as nausea, anemia, and memory problems.
However, it was difficult to identify patients who no longer needed treatment, and the researchers wanted to see if a blood test could be helpful.
The study looked at 455 patients who underwent surgery because their cancer had spread to the wall of the colon. After surgery, one of the groups underwent a blood test – customized according to the tumor’s genetic profile – to detect any remnants of the cancer’s DNA.
Their care was based on the results of the analysis: if no trace of cancer was detected, the patients did not receive chemotherapy. Doctors decided on chemotherapy for other patients in the usual way, guided by the analysis of the tumor and surrounding tissues.
Fewer patients in the blood test group received chemotherapy – 15% versus 28%. But about 93% of patients in both groups were still cancer-free after two years. This means that the first group did it the same way, but with less chemotherapy.
“In patients in whom cancer DNA is not detected after surgery, the risk of cancer recurrence is very low, indicating that these patients are unlikely to benefit from chemotherapy,” said study author Dr Jane Tay from the Peter McCallum Cancer Center in Melbourne. . Australia.
Avoiding chemotherapy makes a “big difference to a person’s quality of life if it can be done without risking relapse,” said Dr. Everett Fox, president of the American Society of Clinical Oncology.
The other study followed 500 slightly older women with a common form of early-stage breast cancer and low levels of the Ki67 protein, an indicator of more aggressive cancer.
After surgery, the women took pills to block the action of hormones, a common treatment for this type of cancer, but they did not receive radiation therapy.
Five years later, ten women watched the cancer return to the same breast, and there were deaths attributed to breast cancer. There was no control group, but the researchers say their results compare favorably with historical data for similar patients treated with radiation.
“We estimate that the benefits of radiation would be very modest in this population, compared to the side effects,” said study author Dr. Timothy Whelan of McMaster University in Ontario. Her work has been supported by the Canadian Breast Cancer Foundation and the Canadian Cancer Society.
Radiation can cause skin problems and fatigue, and rarely, long-term heart problems and secondary cancers.
Dr. Deborah Axelrod of NYU Langone Health, who was not involved in the work, said.
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