Male Breast Cancer: Warning Signs, Biology, and Genetic Testing

Breast cancer in men is rare, accounting for less than 1% of all breast cancer diagnoses in the United States. The American Cancer Society estimates that about 2,670 men will be diagnosed with invasive breast cancer in 2026 and about 530 will die of the disease; the average lifetime risk for men is about 1 in 755. Because there are no dedicated screening guidelines for men, and because breast cancer is widely perceived as a women's disease, male patients are often diagnosed at later stages.

In an interview with Oncology Nursing News during Breast Cancer Awareness Month, Brianne Whitley, CNP, a nurse practitioner who practices primarily in breast oncology at Dana-Farber Cancer Institute in Boston, Massachusetts, discussed what nurses and primary care providers should watch for and how male disease differs from female breast cancer.

Whitley stressed that a painless mass behind the nipple, new nipple inversion or discharge, or lumps under the arm warrant prompt evaluation. She noted that most male breast cancers are estrogen receptor (ER)–positive, which has made tamoxifen, taken for 5 to 10 years, the long-standing treatment backbone.

She also emphasized that National Comprehensive Cancer Network (NCCN) guidelines recommend genetic counseling and testing for all men diagnosed with breast cancer, regardless of family history. Previous Oncology Nursing News coverage has highlighted how clinician awareness can shorten the time to diagnosis and treatment for men.

Given that male breast cancer is often diagnosed at later stages, what distinct warning signs or clinical indicators should nurses and primary care providers emphasize during routine screenings?

I think an important thing to note is just how rare male breast cancer is in general. I think that comes along with why sometimes it's not detected as early as it is in women, because there's not dedicated screening guidelines necessarily. So I think the most important thing is that any mass that is felt, whether it's firm, behind the nipple, retroareolar, or off center, or even if there's any new inversion of the nipple, retraction, any nipple discharge, including bloody nipple discharge, any lumps that are felt under the armpits—those would be all things to bring to attention right away.

I think that a lot of the time it's found at later stages because it's not painful. The patient may not bring it to anyone's attention, but like anything else, early detection is key. So as soon as you feel something, bring it to the attention of your provider to get prompt diagnosis and testing.

How can oncology nurses help male breast cancer patients overcome social stigmas and feelings of isolation that are often associated with receiving a diagnosis that's predominantly linked to women?

I think this can be difficult. I think one way is educating that anyone who has breast tissue can get breast cancer, and even males do have a small amount of breast tissue. So it's just important to note that from an anatomical standpoint. And also just acknowledging that most of the resources are aimed at our female population, [which] can lead to more isolation and stigma.

But I think there is increasing awareness, fortunately, which can help. I think that connecting with other male patients who have had a similar diagnosis can be helpful. Also, presenting educational materials that are directed toward our male patients—whether that be in the surgical context, for example, providing any diagrams that may have male anatomy instead of female. Things like that could be helpful. Really patient-centered care.

What key differences in tumor biology, biomarker presentation, or treatment strategies should oncology nurses keep in mind when they're managing male breast cancer compared with female breast cancer?

I think one of the key differences [is that] most male breast cancers tend to be hormone driven. So most of them actually are ER positive, and it is much less common to see HER2-positive, although there can be, and even more so triple-negative disease, which is a little different than our female breast cancer population.

Because of that, even though the treatment can be similar in terms of whether or not it includes chemotherapy, endocrine therapy, surgery, and radiation, because most of the cancers are hormonally sensitive, the main backbone for a lot of time has been tamoxifen, taken for 5 to 10 years, which is a blocker of the estrogen receptor. And so I think just knowing that it's predominantly estrogen receptor–positive biology, and then knowing the trickle-down effect of what that treatment will mean in terms of using estrogen receptor–blocking treatments like tamoxifen.

How critical is immediate genetic counseling and BRCA testing for men who are diagnosed with breast cancer, and what role do nurse practitioners play in navigating these discussions for both patients and their families?

I would say in the male breast cancer space, it's essential. And actually, the NCCN guidelines recommend that all male patients who are diagnosed with breast cancer, regardless of their family history, are promptly referred for genetic counseling and testing. And that's because there usually is a strong genetic link. I think it's an estimate of 10% to 15% [that] would be BRCA1 or BRCA2 linked. And there could also be CHEK2, PALB2, or ATM, among other variants.

So I think in terms of the nursing and the nurse practitioner role, it would mostly be ensuring that you get that referral in promptly, because it can play a role in guiding treatment decisions, potentially the surgical approach and the treatment after.

Editor's note: This transcript has been lightly edited for clarity and length.

References

1. Key statistics for breast cancer in men. American Cancer Society. Updated January 13, 2026. Accessed October 20, 2026. https://www.cancer.org/cancer/types/breast-cancer-in-men/about/key-statistics.html
2. Program for Breast Cancer in Men. Dana-Farber Cancer Institute. Accessed October 20, 2026. https://www.dana-farber.org/cancer-care/treatment/breast-oncology/programs/breast-cancer-in-men
3. NCCN Clinical Practice Guidelines in Oncology. Genetic/familial high-risk assessment: breast, ovarian, pancreatic, and prostate. National Comprehensive Cancer Network. Accessed October 20, 2026. https://www.nccn.org/guidelines/category_2
4. Cutrone J. Joaimee Cutrone on raising awareness of male breast cancer. Oncology Nursing News. May 5, 2017. Accessed October 20, 2026. https://www.oncnursingnews.com/oncnurse-tv/joaimee-cutrone-on-raising-awareness-of-male-breast-cancer