By Debbie Kim, WBZ-TV

BOSTON (CBS) — How far would you go to protect yourself if you knew you carried a gene that caused a deadly form of cancer and watched your brother die of the disease?

One local family went to extreme measures to help save themselves from a rare form of stomach cancer.

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80-year-old Mary Walsh has been battling colon cancer since 2005. That same year, her son Steven was also diagnosed with stomach cancer.

By chance, Mary’s doctor just happened to notice that both of their cancers were caused by the same rare genetic mutation. So after Steven died, all four of his surviving siblings got tested to see if they also carried the same gene.

Mary Walsh explains, “We’re sorry we lost him but because of him we were able to save the others.”

Even before they were tested, all of Mary’s kids decided that if they did have the mutation, they would take a drastic step —  undergo surgery to have their stomachs removed. Only one brother didn’t have the gene. The other three siblings did.

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Beth Lambert explains, “When we first learned about this, it was shocking to us, we didn’t know you could live without a stomach but when you look at the option and we saw our brother Steve really suffer and that made the decision really easy.”

Michael Walsh agrees, “After watching our brother going through being sick, was really the only choice we had.”

It was a choice that saved their lives because it was only after the surgery that doctors discovered that all three siblings did in fact have stomach cancer.

So now all of their children are getting tested; three of Shannon’s cousins have already tested positive for the gene.

“It makes me feel a lot better to know that you can do something about it if I do have it.”

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The Walsh family is now working with a group called No Stomach for Cancer to help educate families and doctors about the rare hereditary cancer their family suffered from. They’re hoping their story will encourage others to learn more about their genetics and their families November has been declared Stomach Cancer Awareness month.