By Karuna Jaggar, Executive Director
Because so many breast cancer patients live for many years after their initial treatment, and even some metastatic breast cancer patients are living longer, there’s a growing focus on striking the right balance of treatment: neither over nor under treating patients.
This is true not only for systemic therapies and surgery, it’s also true for radiation therapy (sometimes also called radiotherapy). There have been a lot of changes over 40 years that have reduced some of the worst toxicities of radiation, and more changes are on the horizon.
In the last decade the length of breast radiotherapy has been cut in half. Radiation treatment has gotten more effective, as an EBCTCG meta-analysis (GS4-02) of regional node irradiation in early breast cancer found, concluding that regional node irradiation had little effect on breast cancer mortality before 1978, but since 1989 newer trials have shown breast cancer mortality significantly reduced. And newer techniques and devices are able to reduce the toxicities and side effects from radiation therapy to treat breast cancer. While it is not without harms, radiation therapy has an important role in saving lives, in helping to avoid mastectomy, and in reducing other quality of life harms.
Older trials found that women who were successfully treated for breast cancer were then dying of heart disease. But modern techniques and tools, including doing radiation at an angle to avoid the heart, and having patients hold their breath, has dramatically reduced the life-threatening outcomes from radiation. The EBCTCG trial showed that contemporary radiotherapy treatment improves the risk-benefit ratio, which, given many people are extremely reluctant to have radiation therapy based on fears from outdated methods, may shift the calculus for patients as they consider their treatment options.
Radiation can help reduce the need for or extent of surgery. It’s of course been used for years paired with lumpectomy to let people choose breast conserving surgery instead of mastectomy, with even slightly better mortality outcomes. And a Dutch study presented at SABCS found that radiation can also be used instead of surgery to treat lymph nodes.
The Dutch team presented 10 year follow up results of the EORTC AMAROS trial (EORTC 10981/22023) (GS4-01), which compared radiation therapy or surgery to treat early breast cancer with positive sentinel node. Patients in both groups had the same overall survival and disease-free survival after radiotherapy to the axilla, instead of removing additional lymph nodes. But the difference between the two groups were the reduced side effects for those people treated with radiation: avoiding surgical removal of the lymph nodes cut the rates of lymphedema by half at five years, which is a dramatic quality of life benefit.
Only 1 percent had a recurrence, and when they did, it tended to return to the lymph nodes. In fact, there were so few “events” that when the presenter showed the 10 year results he quipped: “nothing happened, thank you for your attention.”
Having shown that radiation reduces harmful side effects, compared to surgery without compromising 10 year outcomes for low risk patients with 3 or less positive nodes, the next question is whether low-risk patients need to have their lymph nodes treated at all. They do so well in the first place, maybe they can skip both axillary dissection and radiation!
Partial breast radiation, rather than whole breast radiation, is another area of interest to see if harms can be reduced without impacting outcomes. In those rare situations where a cancer grows back after lumpectomy and radiation, it usually does so at the original site (scar, etc.), causing researchers to wonder if it would it be possible to just radiate tumor bed, not whole breast.
Two similar studies about partial breast irradiation were presented on Thursday: RAPID (GS4-03) and NSABP B-39/RTOG 0413 (GS4-04). I’m not going to get into the weeds on these studies, which reached different conclusions on whether partial breast irradiation is, or is not, inferior to whole breast irradiation. But the gist is, it’s going to take more confirmatory studies to resolve the issue and there is ongoing research into several different partial breast irradiation techniques, so there is more to come. The hope is newer techniques will continue to minimize harms, without compromising outcomes.