Radiation may not be needed for some early-stage breast cancers

Hormonal therapy alone following surgery may be enough to prevent local recurrence in some people with early-stage hormone receptor-positive breast cancer. Research presented on June 7, 2022, at the annual meeting of the American Society of Clinical Oncology may support changing the treatment guidelines for certain breast cancers to reflect the findings of this study.

Background

Treatment for early-stage breast cancer continues to change over time. In the past, doctors treated all breast cancers aggressively, using every therapy at their disposal. The impact on quality of life could be substantial, as people spent more months in treatment, and each treatment brought its own side effects.

Today, more sensitive screening means more breast cancers are diagnosed very early. Surgery has also improved, as surgical oncologists use new techniques to see and remove the cancer. Drug and radiation therapies are more precise and tailored to the individual’s cancer. Yet, doctors still are mostly unable to predict which breast cancers will return.

Ongoing studies try to answer this question – looking for markers of cancers that are more or less likely to return. The goal is to avoid overtreatment – to determine which therapies are truly needed to complete treatment and prevent the cancer from coming back.

Radiation is often effective but also can be costly and challenging because of the number of treatments. It can cause side effects such as fatigue, skin irritation and redness, and pain. It is often used with hormonal therapy, which is also highly effective in preventing recurrence in low-risk hormone receptor-positive, HER2-negative breast cancers.

Results

Based in Canada, the LUMINA clinical trial sought to find out if some people with early-stage breast cancers could be spared radiation therapy. It was a carefully controlled, prospective cohort study, which in this case followed a group of people over time to see whether there were differences in their breast cancer outcomes. The study investigators focused on people with the Luminal A subtype of breast cancers, which past research shows has a low risk for local recurrence (coming back in the same area).

In this trial, Luminal A breast cancers were defined as testing positive for both estrogen and progesterone receptors and negative for HER2 receptors, and having a Ki-67 score of less than or equal to 13.25%. Ki-67 is a protein; a lower Ki-67 score means that breast cancer is not growing as quickly and is less likely to come back after treatment.

The study included 500 women ages 55 and older. They all had Luminal A, HR-positive, HER2-negative early-stage ductal breast cancer. Staging was determined by the TNM Staging System. Study participants had very small tumors (T1) and no cancer in the lymph nodes (N0). They all underwent lumpectomy followed by hormonal therapy for 5 years.

Trial staff followed participants for 5 years to see if their cancers returned. Participants had mammograms every 6 months for the first 2 years, and then annually.

The results fell far within the goals of the study. Only 12 people in the study had breast cancer return, 10 of which were local recurrences in the same area. As a result of the study design and the findings, some physicians at the meeting felt this information could immediately be used to guide clinical practice.

What this means for you

The findings from this study could alter the treatment guidelines for a subgroup of people with early-stage hormone receptor-positive, HER2-negative breast cancer. The research team estimates that this change could affect the breast cancer treatment of between 30,000 and 40,000 people in North America each year.

If you recently learned you or someone you care about has early-stage, hormone receptor-positive, HER2-negative breast cancer, talk with your oncologist about your treatment plan. If they recommend radiation, ask if they have heard about the recent findings from the LUMINA study. Do these findings apply to your situation?

It’s worth noting that all participants in this study were women. The median age of participants was 67 (half were younger, half were older), so the findings are unlikely to influence treatment for premenopausal women. These results may not be relevant to men with breast cancer, transgender men, and non-binary individuals.