The seatbelt across Pete Passanisi’s chest felt uncomfortable. Whenever he got in his car and pulled it across, pain shot across the left side of his chest where the nylon belt touched.

At first, he thought it was just a pulled muscle or heartburn, but when his family encouraged him to do a self-examination, he noticed a number of small, hard bumps that felt like bits of rock candy.

In December 2011, Passanisi, then 66, went for a biopsy at his local hospital in Lake Saint Louis, Missouri, and one day after Christmas, learned those bumps were cancerous. He was diagnosed with stage two breast cancer and was given a single mastectomy with lymphadenectomy a few days later.

“The seatbelt saved his life,” says his daughter Annie Passanisi-Ruggles. The 27-year-old learned a few months after her father’s operation that she carried the same faulty gene that had led to her father’s cancer. The mutation in the BRCA2 gene significantly increases her risk of developing breast and ovarian cancer.

Today, Annie’s on a six month rotation of preventative cancer screenings that include MRIs and mammograms. “If the gene does express, she’ll catch it early,” says Pete.

You might also like:

• Why Alzheimer’s hits women harder than men

• Why non-smokers are getting lung cancer

• What’s the worst time of day to get sick

The BRCA1 and BRCA2 genes are tumour suppressors that are responsible for repairing faults that can naturally occur within DNA. When they do not function correctly, it makes it more likely that other genetic errors will occur, leading to cancer.