20 November 2019

One of the challenges in treating male breast cancer is that there are few studies specifically focusing on men. Breast cancer is much less common in men than in women (approximately 2600 versus 260,000 cases per year in the US). However, men tend to be treated using the same protocols that are used for women – even though we don’t know if that is the most effective approach.

For women with stage 1-2 breast cancers that are estrogen receptor positive (ER+) and Her2/neu not over-expressed (Her2-), additional tumor testing is commonly performed to determine whether or not chemotherapy would be of benefit. The Oncotype Dx test, one of several commercially available genomic tests, has only been validated in women. Researchers recently evaluated whether the Oncotype Dx test has the same prognostic ability in men as it does in women. 

The researchers used the National Cancer Database to identify women and men diagnosed with stage 1 and 2, ER+ and Her2- breast cancer between 2010-2014, for whom Oncotype Dx recurrence scores (RS) were available. 848 men and 110,898 women were identified. Associations between mortality and RS were determined. Overall mortality was 41 for men and 2527 for women. 

Findings included*:

  • Men had a higher proportion of RS ≤10 or ≥31 versus women
  • Use of chemotherapy increased with higher RS for both men and women
  • Among patients with RS ≥26, 70.9% of men and 74.8% of women received chemotherapy
  • In men, increasing RS were associated with increased likelihood of death up to a RS of 21, after which the risk plateaued
  • In women, RS was only associated with an increased likelihood of death above a RS of 23 
  • A concluding statement: “…RS is prognostic for total mortality in both male and female patients, but with distinct association patterns. Mortality increased in much lower ranges of RS for male than female patients with breast cancer.”

Some limitations of the database review were that only overall, not breast cancer-specific mortality could be assessed (so we do not know why the patients died), and there was no information on specific details of treatment or adherence to treatment. However, this study does provide some insights into the biological differences between breast cancer in men and women, and the researchers called for more study evaluating whether the RS is predictive of chemotherapy benefit in men with breast cancer.

*If you are not able to access the full study and would like a copy, please email me: contact at drattai dot com

AACR Press Release