A human melanoma cell line. (Plinio R. Hurtado/iStock)

By the time oncologist and genetics researcher Theodora Ross got her MD and PhD, she needed both hands to count the number of her relatives who had cancer. After her beloved sister Bea died of breast cancer at 38, Ross became determined to study the so-called “breast cancer genes,” BRCA1 and BRCA2.

Then Ross was diagnosed with melanoma and during her treatment learned that she had a BRCA1 mutation. “This was the experience that changed my life,” she writes — and not only for the obvious reasons. “I’d always wanted to study the BRCA1 gene . . . but I couldn’t — at least not in the way I wanted to — because I wasn’t ethically or legally able to ask another person to fork over his or her genetic material. Now . . . I could study myself.”

And so begins “A Cancer in the Family: Take Control of Your Genetic Inheritance,” in which Ross combines her personal story with professional information. In sections with such titles as “Why Not ‘Just Get Tested’?” and “Biology Isn’t Destiny” she tackles issues that face more and more people as scientific knowledge and capabilities expand in unwieldy, hard-to-understand ways. And she’s disarmingly honest about how her extensive education gave her no advantage as a patient. “I’m a fan of people like Angelina Jolie and Christina Applegate,” she says, calling them “ideal patients” for being publicly forthright about their BRCA1 mutations and their decisions to “just get the job done” by having preventive surgery. “It may go without saying that I was not one of these ideal patients,” she writes. “It wasn’t just that I was in denial. . . . I felt embarrassed and even ashamed.”

In a praise-filled forward to the book, Siddhartha Mukherjee — author of the Pulitzer-winning “The Emperor of All Maladies” — writes: “This book is like having a comforting chat with a passionate doctor and researcher who is also your friend — the kind of friend who can weave together accessible science, personal stories, and practical suggestions.”