In some older breast cancer patients, skipping radiation therapy after they've had surgery doesn't appear to have a detrimental effect on their overall survival, according to a new study.
Skipping radiation after surgery may not affect overall survival for women 65 and older with small hormone-positive breast cancer tumors, provided that they receive five years of endocrine therapy, says the study, published Wednesday in . But it may be associated with a higher risk of cancer returning in the same breast.
The findings suggest that radiation -- which can have side effects such as fatigue, breast pain, as well as the risk of heart and lung complications -- may not be needed to extend overall survival among this group as long as they have endocrine therapy. Endocrine therapy -- also called hormone therapy -- involves adding, blocking or removing hormones as part of a treatment approach for certain conditions, including to slow or stop the growth of certain cancers.
"These data offer a response to the long-standing problem of overtreatment in older women with low-risk breast cancer," Dr. Alice Ho of Duke University School of Medicine and Dr. Jennifer Bellon of Harvard Medical School published alongside the new study.
"The ability to omit radiotherapy is one of many options in a lengthy list that also includes the use of abbreviated radiotherapy regimens and smaller target volumes," Ho and Bellon wrote. "Pragmatically, radiotherapy can strain time and finances. Therefore, robust data solidifying the option to omit radiotherapy in selected patients are welcome."
The study included data on 1,326 women with breast cancer who were 65 and older. From April 16, 2003, to December 22, 2009, 658 of the women were randomly assigned to receive radiation therapy across their whole breast, and 668 of them received no radiation therapy. The trial was conducted across 76 centers in the United Kingdom, Greece, Australia and Serbia.
The researchers found that cancer recurrence in the same breast was more common in the participants who did not get radiation; the cumulative incidence of local recurrence was 9.5 per cent in the no-radiation group and 0.9 per cent in the radiation group.
"The incidence of local recurrence up to 10 years among patients who received radiotherapy remained low, whereas that among patients who did not receive radiotherapy continued to increase with no apparent plateau. However, the absolute difference in the incidence of local recurrence at 10 years was modest," the researchers, from the University of Edinburgh and Western General Hospital in Scotland, wrote in the study.
And overall survival at 10 years was nearly identical: 80.8 per cent without radiation therapy and 80.7 per cent with it, the researchers found. Sixteen deaths in the no-radiotherapy group and 15 deaths in the radiotherapy group were due to breast cancer.
Previous research has supported excluding radiation in women older than 70 with small tumors -- less than 2 centimeters -- but this new study provides evidence for lowering the age limit to 65 and including women with tumors up to 3 centimeters, said Dr. Naamit Kurshan Gerber, a radiation oncologist at NYU Langone Perlmutter Cancer Center in New York, who was not involved in the research.
In the United States, 26 per cent of breast cancer diagnoses are in women ages 65 to 74, according to the study.
"So we've had evidence before this paper that in women over 70, adding radiation lowers the risk of local recurrence, but it doesn't change survival. And this study is really adding to the weight of that evidence, but it's also, of course, lowering the age from 70 to 65," Gerber said. "The role of radiation in these women is really reducing this risk of local recurrence, which it does, but there's really no effect on overall survival."
Some breast cancer patients might decide to skip radiation for various reasons -- including side effects -- but others may still choose to have radiation therapy to lower their risk of cancer recurring in the same area.
But Gerber added that for breast cancer patients who are not planning to take endocrine therapy, skipping radiation is not an option.
For doctors and patients, "it's very important to engage in shared decision-making about what are your values, what are your goals, and sort of explaining the risks and the benefits of radiation therapy and, of course, the benefit is preventing a local recurrence," Gerber said.
"There are risks, there are side effects, but it's always a very nuanced discussion," she said. "There's no one right answer for every single person."
