Breast cancer and radiation therapy : Dr. Nilesh D. Mehta

ASCO 2022 : Breast cancer and Radiation Therapy: June  2022 : Dr. Nilesh D. Mehta 

1 in 3 people will be diagnosed with cancer in their lifetime. With regards to breast cancer, 287000 women are likely to be diagnosed in 2022 which represents 15% of all cancers in women. Nearly 43000 deaths are likely to be attributed to breast cancer in 2022 which represents 7.1% of all cancer deaths. 

 

Treatments for breast cancer have evolved over the last several decades and modifications in the treatment recommendations have also been evolving. Historically, radiation therapy (RT) has been a key component of the treatment for breast cancer patients after lumpectomy with an attempt to reduce local recurrences in the breast. 

 

However, it became apparent over the last few decades that some women with good prognosis breast cancer did not need radiation therapy following their lumpectomy. Hence with the goal of omitting RT in treating luminal A-type breast cancer (13.25% or less of tumor cells exhibiting protein marker Ki-67), a large Canadian study was initiated several years ago in women 55 of age or older with breast cancer. 

 

Adjuvant breast RT is usually prescribed following breast conserving surgery to reduce the risk of local recurrence. However, this treatment is inconvenient, costly, and associated with acute and late toxicity. Traditional clinical pathological factors  alone are limited in their ability to identify women with a low enough risk of local recurrence to omit RT. Molecular defined intrinsic subtypes of breast cancer provide additional prognostic information with luminal A having the lowest risk of recurrence. Previously, retrospective analysis of a previous trial suggested that women >60 years with luminal A grade 1-2 T1N0 breast cancer  treated by BCS and endocrine therapy alone had a low rate of LR (published in Journal of Clinical Oncology 2015; 33:2035). 

 

According to Corey Wayne Speers, MD, PhD, ASCO Expert in radiation oncology : “This exciting data is very reassuring and could impact a large number of patients with cancer who have very low chances of their breast cancer returning even without radiation therapy. These findings are the first of a number of recent trials in breast cancer looking at reducing treatments that are still commonly used but that may not be necessary for appropriately selected patients,” 

 

It is very important in medical therapeutics when not to prescribe a certain treatment. Revisiting previously accepted gold standards can lead to new information which can have a strong and meaningful impact in patient care thus establishing newer gold standards. 

 

In summary, based on guidance from biomarker screening, patients who are 55 years of age and older with low-grade luminal A-type breast cancer may only need endocrine therapy following breast conserving surgery and could avoid radiation therapy entirely, according to new research findings that was presented at the 2022 American Society of Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois. With thousands of women being diagnosed annually with invasive breast cancer in North America, it is estimated that through this particular clinical trial results, as many as 30,000 – 40,000 women per year could avoid the morbidity, inconvenience, and cost of RT. This is truly a practice altering study which medical and radiation oncologists will apply in their practices.