The research was discussed at the annual meeting of the American Society of Clinical Oncology, which ended Tuesday in Chicago. The colon cancer study, funded by the Australian and US governments and non-profit groups, was published in the New England Journal of Medicine on Saturday.
The results could allow doctors to “focus on patients who we think would really benefit from chemotherapy and avoid side effects for patients where it is unlikely to be needed”, said Dr Stacey Cohen. from the Fred Hutchinson Cancer Center in Seattle, which examined colon cancer. results and did not participate in the research.
Many colon cancer patients receive chemotherapy after surgery, even though they can be cured. The drugs can cause side effects such as nausea, anemia, and memory problems.
But identifying patients who might not need further treatment has been tricky. Scientists investigated whether a blood test could help doctors make the call.
The study involved 455 patients who underwent surgery because the cancer had spread into the wall of the colon. After surgery, one group received a blood test, matched to the genetic profile of their tumour, to detect any remaining bits of cancerous DNA.
Their management was guided by the blood test: if there was no sign of residual cancer, the patients did not receive chemotherapy. Meanwhile, doctors made chemo decisions for the rest of the patients in the usual way, guided by analysis of the tumor and surrounding tissue.
Fewer patients in the blood test group received chemotherapy – 15% versus 28%. But about 93% of both groups were still cancer-free after two years. In other words, the blood test group did just as well with less chemotherapy.
“In patients in whom cancerous DNA is not detected after surgery, the risk of cancer relapse is very low, suggesting that chemotherapy is very unlikely to benefit these patients,” said Dr. Jeanne Tie of the Peter MacCallum Cancer Center in Melbourne, Australia, who conducted the research.
Skipping chemo makes “a big difference in a person’s quality of life if it can be done without having to put them at risk of recurrence,” said ASCO President Dr. Everett Vokes, who specializes in chemo. head, neck and lung cancer at the University of Chicago. Medicine.
The other study followed 500 older women with a common form of early-stage breast cancer and low levels of a protein known as Ki67, a fast-growing cancer marker.
After the surgery, the women took hormone-blocking pills, a standard treatment for this type of cancer, but they did not receive radiation therapy.
After five years, 10 of the women saw the cancer come back in the same breast and there was one death from breast cancer. There was no comparison group, but the researchers said the results compare favorably with historical data from similar patients who underwent radiation therapy.
“We estimate that the benefits of radiation therapy would be very small in this population compared to the side effects,” said Dr. Timothy Whelan of McMaster University in Hamilton, Ont., who led the study, which was supported by the Canadian Breast Cancer Foundation and the Canadian Breast Cancer Foundation. Canadian Cancer Society.
Radiation can cause skin problems, fatigue and, less commonly, long-term heart problems and secondary cancers.
The study is a ‘feel good’ message for patients with low-risk tumors and will help doctors understand which of their patients they ‘can comfortably, confidently’ omit radiation, said Dr Deborah Axelrod from NYU Langone Health, which was not involved in the research.
The Associated Press Health and Science Department is supported by the Howard Hughes Medical Institute Department of Science Education. The AP is solely responsible for all content.