After surgery, some cancer patients can safely skip radiation or chemotherapy, according to two studies of shorter, gentler cancer care.
Researchers are looking for ways to predict which cancer patients can avoid unnecessary treatments to reduce harmful side effects and high costs.
A new study used a blood test to determine which colon cancer patients could skip chemotherapy after surgery. Another suggests that some low-risk breast cancer patients may omit radiation after a lumpectomy.
The research was discussed at the American Society of Clinical Oncology annual meeting, which concluded Tuesday in Chicago. The colon cancer research, funded by the Australian and US governments and nonprofits, was published Saturday by the New England Journal of Medicine.
The findings could allow doctors to “focus on the patients we think will really benefit from chemotherapy and avoid the side effects for patients who probably don’t need it,” said Dr. Stacey Cohen of the Fred Hutchinson Cancer Center in Seattle, who assessed colon cancer. Findings and was not involved in the study.
Many colon cancer patients receive chemotherapy after surgery, even though it may be curable. The drugs can have side effects such as nausea, anemia, and memory problems.
But it was difficult to determine which patients did not need further treatment. Scientists have investigated whether a blood test can help doctors make calls.
The study involved 455 patients who had surgery because cancer had spread to the colon wall. After surgery, one group was given a blood test matched to the genetic profile of their tumor to detect any remaining pieces of cancer DNA.
Their concern was guided by the blood test: if it showed no signs 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 nearby tissue.
Fewer patients in the blood test group received chemo – 15% vs. 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 whose cancer DNA is not detected after surgery, the likelihood of cancer recurrence is very low, suggesting that chemotherapy is very unlikely for these patients,” said Dr. Jeanne Tie of the Peter MacCallum Cancer Center in Melbourne, Australia, who led the research.
Skipping chemo makes “a big difference in a person’s quality of life if that can be done without putting them at risk for recurrence,” said ASCO president Dr. Everett Vokes, who specializes in head and 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 marker of fast-growing cancer.
After surgery, the women took hormone-blocking pills, a standard treatment for this type of cancer, but received no radiation.
After five years, 10 women saw cancer recur in the same breast, with one death from breast cancer. There was no comparison group, but researchers said the results compare favorably with historical data for comparable patients who had radiation treatment.
“We estimate that the benefits of radiation in this population are very small compared to the side effects,” said Dr. Timothy Whelan of McMaster University in Hamilton, Ontario, who led the study, which was supported by the Canadian Breast Cancer Foundation and the 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 of NYU Langone Health, who was not involved in the study.
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