"I want to save lives, especially in the Black community," Knowles says

The first time Mathew Knowles spotted a pinprick-size red dot on his shirt, in July 2019, he didn’t think much of it. Nor the next day, when the music producer and father to superstars Beyoncé and Solange found another spot on his shirt.

When it happened a third time, though, Knowles, 68, brought it up to his wife of seven years, Gena Avery Knowles, who said she had noticed similar spots on their bedsheets. “I said, ‘Okay, I need to go to the doctor,’ ” he tells PEOPLE.

Knowles had learned to be cautious about his health after years selling medical imaging equipment, including mammography machines. He had to know the ins and outs of the technology and the medical conditions, so he knew that men can get breast cancer and that one of the signs is nipple discharge, much like what he was now seeing on his shirts.

And a few days later, a mammography and biopsy confirmed his suspicions — Knowles was one of the few men diagnosed with breast cancer, about 1 percent of the 270,000 breast cancer cases that are found each year.

“I was in disbelief,” he says.

matthew and beyonce knowles
Mathew and Beyonce
| Credit: Dave Hogan/Getty

For more on Mathew Knowles’ battle with breast cancer, pick up the latest issue of PEOPLE, on newsstands Friday.

Knowles, though, was lucky. He had caught his cancer early, when it was Stage 1A, meaning it was small and had not spread to the lymph nodes. He didn’t need chemotherapy, but he did need a mastectomy. And telling Gena was one of the hardest parts.

“Less than a year earlier, her younger sister had died of breast cancer at 49 years old,” he says. “It was a difficult period for her, and now her husband has breast cancer. I was just really concerned about her wellbeing and how she would take that.”

matthew knowles and wife
Gena and Mathew Knowles
| Credit: /WiAllen Berezovskyr/Wireimage

Gena says that she was initially in “utter shock,” but hearing that the cancer was caught early brought relief. “I knew he was going to be just fine,” she says.

The couple’s trust in their doctors meant that they also held off on telling Beyoncé and Solange, his daughters with ex-wife Tina Knowles, until after the surgery.

“I wanted the surgery part to be behind me,” he says. “I didn’t want them worrying that this was a life-or-death kind of situation on surgery day.”

The surgery went well, with two quick weeks of recovery. But another surprise came out of his surgery — testing revealed that he had the BRCA2 gene mutation, which raises his risk of developing pancreatic, melanoma and prostate cancers.

matthew knowles
Mathew Knowles
| Credit: Courtesy Mathew Knowles

“All those years I’ve been in diagnostic imaging, I had never heard the word BRCA before,” Knowles says.

That pushed him to look into his family history. Knowles knew that his mom and aunt had died of breast cancer, but he also learned that his great aunt died of it as well, and four of his father’s six brothers had died of prostate cancer.

Knowles “immediately” went back to his doctor for MRIs of his prostate, pancreas and liver, and goes for regular skin cancer checks. “If I had known about the BRCA gene, I would’ve had a double mastectomy,” he says.

And now, he wants everyone to find out if they have the BRCA gene so they can be proactive about their health. Knowles started working with Invitae, a genetic testing company, at the start of the year to encourage everyone to get tested  — he’s gotten Beyoncé and Solange to do it too.

“If you’re ahead of the curve, then your outcome will be, most of the time, great,” he says. “I’m a living example.”

Knowles is also making a point of speaking out about male breast cancer, or as he prefers to call it, chest cancer. While men make up just a tiny portion of the breast cancer diagnoses each year, they die at a disproportionately higher rate — 19 percent higher — than women, in part because their cancer is often found later.

“A whole lot has to change in the education of men about breast cancer,” he says.

And he’s placing an added focus on helping Black men, who are diagnosed with breast cancer at a 52 percent higher rate than white men.

“I want to save lives, especially in the Black community,” Knowles says.