Knowles was diagnosed with male breast cancer in 2019, making the announcement to Michael Strahan on "Good Morning America."
In the years since his diagnosis, he's recovered and become an advocate, namely for genetic testing.
"It's about being proactive about your health and getting the information, and once you get the information, getting with your health providers and coming up with a plan," he told ABC13.
Cancer, especially breast cancer, wasn't a foreign concept to Knowles.
He explained that for about eight years in the 80s, he sold mammography equipment, so when he noticed discharge from his nipples and dots of blood appearing on his shirt, his training on the disease helped him to recognize those may be signs of male breast cancer.
He requested a mammogram and confirmed it was cancer.
Male breast cancer isn't common. About 1 out of every 100 breast cancers diagnosed in the United States is found in a man, the Centers for Disease Control and Prevention (CDC) said.
The most common kinds of breast cancer in men are invasive ductal carcinoma and and ductal carcinoma in situ (DCIS).
The most common symptoms are a lump or swelling in the breast, redness or flaky skin on the breast, irritation or dimpling of breast skin, nipple discharge and pulling of the nipple, or pain in the nipple area.
Knowles explained that he had a mastectomy, but he felt what was really key to understanding the overall picture of his health was genetic testing.
"That kind of changed everything when I found out I was BRCA mutated," he said, adding that he's BRCA2 positive, specifically. "It means for men that you have a higher risk, not necessarily that you will get it, but a higher risk of male breast cancer, pancreatic cancer, prostate cancer as well as melanoma. For women, it means ovarian cancer possibly as well as breast cancer."
"I think it's absolutely critical that today we start with getting a genetic test," Knowles added.
Today, Knowles has partnered with AstraZeneca on its BeBRCAware campaign, aimed at educating people about genetic testing, knowing their family history and the risks for cancer.
Knowles said he knew going back to his grandmother on his mother's side of breast cancer in his family. On his father's side, his grandfather died of prostate cancer, as did four of his dad's brothers.
But the testing can also give you insight into other diseases and potential health challenges, Alzheimer's and risk of strokes.
Knowles, also a global ambassador for 23andMe, said most people might be afraid, thinking testing is invasive or painful, but it's only a saliva test.
Since continuing his advocacy, Knowles says he's received positive feedback from men who may have felt shame having breast cancer.
"I've had a number of men whisper in my ear, 'You know, I have that, too,' but I have wanted to be out in the open, out in the public because once you talk out loud, it loses its energy," he said. "I think it's important for men and women to understand the importance of early detection, especially men and women of color to understand how important it is to find these diseases early."
Knowles was diagnosed with Stage 1A cancer and says he leads a very normal life.
"Things happen differently at Stage 4, it's a lifestyle change that I've done. I've lost weight. I've changed my eating habits. I've exercised," he told ABC13. "Then there's the mental health part of this that a lot of people don't talk about that's very important. Not to isolate if you do find out that you have this disease."
And knowing your BRCA status, he says, can help make that huge difference. "Knowledge is power."
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