COULD PATIENTS WITH UNAGGRESSIVE BREAST CANCER skip radiation therapy, a historically important tool for most patients having a lumpectomy for early breast cancer? Breast Cancer: Less is More?

A new study suggests we may someday ditch radiotherapy for highly selected patients with early breast cancer. While we need longer follow-up, the research is promising.

Today, we look at this breakthrough finding, reported this week at the Annual Meeting of the American Society of Clinical Oncology.

Early breast cancer basics

Radiation therapy is a treatment that typically uses high-energy rays that can destroy cancer cells. Radiation therapy is usually indicated after breast-conserving surgery to lower the chances cancer will come back in the same breast or neighboring lymph nodes.

Unfortunately, while radiation therapy (RT) can remarkably reduce the chances of cancer returning to the breast, RT can be costly and has some potential associated toxicities.

Moreover, in recent years, modern imaging and surgical techniques (including closer attention to getting a cancer-free zone — a margin — around cancer) have greatly improved cancer control.

Radiation therapy can also improve long-term survival odds for most patients with early breast cancer. For example, researchers of Oxford University (United Kingdom) demonstrated that for every six patients who suffer a local or regional cancer return by ten years, one additional breast cancer death would occur by 15 years.

Breast cancer: A new treatment approach

Canadian researchers analyzed 500 patients with breast cancer. None had regional spread to underarm (axillary) lymph nodes. All of the subjects were at least 55 years of age. In addition, one could only be in the study if the cancer appeared unaggressive.

What do we mean by an “unaggressive” cancer? For the study, the researchers used a protein marker known as Ki-67. The cancer had to have a Ki-67 proliferation index of 13.25 percent or less, meaning that the cancer did not appear aggressive.

In terms of stage, the participants all had early (T1, N0, M0) breast cancer — none had primary cancers over two centimeters in size or spread to regional nodes or distant sites. The group was clearly highly-selected.

For patients treated with breast-conserving surgery followed by endocrine therapy (pills blocking estrogen from feeding cancer) but not radiation therapy, here are the encouraging results:

• Local recurrence: For 2.3 percent of patients, cancer recurred (came back) in the same breast.
• Contralateral breast cancer: 1.9 percent of patients developed unrelated cancer in the opposite breast.
• Recurrence-free survival: 89.9 percent survived without the disease returning somewhere.
• Overall survival: 89.9 percent

The findings indicate a significant subset of patients with breast cancer who can avoid radiation therapy. This study could be practice-changing if the results hold up long-term and are confirmed by other researchers or in a randomized clinical trial.

While these findings are not practice-changing, I look forward to a day when I offer radiation therapy to fewer patients. On the other hand, endocrine therapy (pills blocking estrogen from feeding breast cancer driven by the hormone) is not always well-tolerated.

Finally, the average age of the patients in the study was in the upper 60s. We already have studies showing similar results to this recent publication.

Thank you for joining me in this look at Breast Cancer: Less is More?

The information I provided in this blog is for educational purposes only and does not substitute for professional medical advice. Please consult a medical professional or healthcare provider if you seek medical advice, diagnoses, or treatment. I am not liable for risks or issues associated with using or acting upon the information in this blog.