Michael Singer had ignored the small lump under his left nipple for months, when he finally decided on a whim to mention it to his doctor during an exam in December 2010.

After a surgical biopsy, Singer returned to the clinic five days later to get his stitches removed and was floored when the doctor said, “Mike, I’m sorry to have to tell you this, but you have stage 2 breast cancer.”

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“I thought, ‘No way — men don’t get breast cancer,'” recalls Singer, a retired federal government facilities manager from New York City, now 57. “What in the world is he talking about?”

Image zoom Michael Singer, Male Breast Cancer Coalition MALE BREAST CANCER COALITION

Although he’d lost his sister, Jo-ann Weiss, to breast cancer just two years before, it never occurred to Singer that breast cancer was an “equal opportunity” killer, with 2,600 men diagnosed yearly and about 440 of those dying because they sought help too late.

Symptoms of breast cancer in men are similar to those in women. According to the American Cancer Society, possible symptoms include: a lump or swelling, which is usually (but not always) painless; skin dimpling or puckering; nipple retraction; redness or scaling of the nipple or breast skin and discharge from the nipples.

“I was embarrassed to talk about my diagnosis, except for telling my wife, Patty,” he tells PEOPLE. “I told everyone else that I had chest cancer because I just couldn’t go there with breast cancer. I felt like a freak. I felt extremely isolated.”

Image zoom Michael and Patty Singer

Then one day, about a year and a half after a successful mastectomy, Singer happened upon a television show featuring men who had survived breast cancer, including actor Richard Roundtree. One of the men, Bret Miller, had founded the Male Breast Cancer Coalition, a nonprofit dedicated to getting out the message that “men have breasts, too.”

Image zoom Michael Singer, Male Breast Cancer Coalition Courtesy the Male Breast Cancer Coalition

“I immediately called them up and Bret’s mom, Peggy Miller, answered the phone and said, ‘Mike, please don’t be embarrassed — we’re fighting to change this stigma, one man at a time,’ ” Singer says. “After I found out about this group, there was no stopping me. I became an activist because I want to help change some men’s lives.”

Image zoom MALE BREAST CANCER COALITION

With the goal of “adding a streak of blue to a sea of pink” during National Breast Cancer Awareness Month, Singer has taken his message to high schools, civic organizations and motorcycle rallies, no longer shy about lifting up his shirt and showing men how to conduct breast exams.

Image zoom Michael Singer, Male Breast Cancer Coalition MALE BREAST CANCER COALITION

“Breast cancer doesn’t discriminate,” Singer, who now goes in annually for a mammogram, or, as he prefers to call it, a “man-ogram,” tells PEOPLE. “Because of Bret and Peggy, I’m now trying to be the voice of guys who don’t want to talk about it or guys who died and can’t talk about it. I want to be that voice that helps change how America looks at men and breast cancer.”

Singer has found a good friend in Bret Miller of Kansas City, who discovered a lump behind his right nipple when he was 17, but was told by his doctor that he simply had “calcium buildup.”

Image zoom Bret Miller Courtesy Peggy Miller

Seven years later, when another doctor recommended that he have a mammogram, he discovered that he had breast cancer and would need a mastectomy.

Image zoom Bret Miller Courtesy Peggy Miller

“It was a terrifying experience,” Bret, now 31, tells PEOPLE, “so I want to tell men not to wait until it’s too late. Early detection saves lives, so go see a doctor if you find a lump, a discoloration or a discharge like I had. If I had known that the yellow-orange discharge I was seeing was a major sign of breast cancer, I would have been proactive and gone in much earlier.”

That’s a message that Singer now shares wherever he goes as well, forever grateful that he summoned the courage to ask his doctor about the lump he found six years ago.