Tracing a Five-Generation Cancer Legacy Through Genetic Discovery

Sue McCarthy received diagnoses of breast cancer in 2001 and lung cancer in 2018. Catch up on all of Sue's blogs here!

My family of origin was never close, emotionally, or for a long time, geographically, either. Until I was 14 years old, we lived in Seattle, Washington, almost 3,000 miles from my grandparents, aunts, uncles and cousins; they all lived in the Mid-Atlantic States.

My parents had issues, and eventually divorced, but that wasn’t until much later. Aside from the summer swim club, my siblings and I spent little time together. I felt isolated, lonely and unloved, and proceeded to make a number of poor choices early in my adult life.

Then, in the course of the first 15 years of the new century, I suffered three major illnesses which led me to want to make positive changes in my life, if I was fortunate enough to recover. Early-stage breast cancer in my late 40s, then the removal of a large benign tumor, a meningioma, from my brain three years later resulted in my developing a stronger Christian faith and increasing my commitment to my church. I started my own business, as well, which I would run successfully for 25 years. And ten years after that I would be diagnosed with stage 3B lung cancer and need to fight for my life. When I reached five years of remission from my disease, I would be deemed cured and subsequently decide to become actively and publicly involved in helping others fight against cancers, all of them.

One of the first things that came to mind soon after I became a lung cancer survivor was to revisit my family’s breast cancer saga, something I had mulled over in my mind from the time I was a young teen, and first heard that my maternal grandmother had suffered from breast cancer as a middle-aged woman in the World War II era. I was impressed; she was a survivor! Then, in 1980, a few months before my first child was born, Grandma’s cancer recurred, and she passed away. In the early 1990s, my mother was diagnosed with breast cancer. It wasn’t long until her cancer metastasized, spreading to her bones, lungs and ultimately, her liver. She struggled through many brutal rounds of chemotherapy, before letting her doctor know that she’d had enough, dying three weeks later.

My breast cancer, duct carcinoma in situ (DCIS), was discovered on a mammogram, just six years after my mother passed away. My oldest daughter was also diagnosed with DCIS; hers was not confined to the milk duct as that type of breast cancer typically is; however, she continues to do well. Both my daughter and I opted for mastectomies followed by reconstructive surgery because of the history of breast cancer in the family. Soon after my daughter’s journey, my aunt shared with me that my great-grandmother had also received the diagnosis. Hence, five consecutive women on the maternal side of my family had received a breast cancer diagnosis.

My daughter and I got BRCA1 & BRCA2 tests at that point. Both of us tested negative. Good news, but… five generations? Maternal side of my family? No genetic link? Was that possible?

In 2019, my daughter took the lead in studying gene mutations, and their connections to cancers. She was tested, and it was determined that she had an Ataxia-Telangiectasia Mutated gene, also known as ATM, as well as CHECK2, a less concerning mutation. We had the first piece of information which would hopefully one day give us a little control over the disease that has been deadly to three women in our family.

The ATM mutation, which my daughter tested positive for several years ago, does not exclusively lead to breast cancer but has a direct link to other cancers: prostate and pancreatic among them. My mother’s brother and his son, my cousin, both had prostate cancer; each was diagnosed at a relatively young age. Both survived their journeys, and although my uncle has since passed away, he lived into his late 80s.

After recovering from prostate cancer, my cousin was experiencing a lot of abdominal pain two and a half years ago in late 2022; he was ultimately hospitalized and diagnosed with Stage 2 Pancreatic Cancer. My cousin was tested for all the genetic mutations that can lead to Prostate and Pancreatic Cancer. Like my daughter, my cousin tested positive for ATM, as well as one other mutation. The determination was that his cancer was primarily caused by ATM. He’s been fortunate to have a clinical oncologist who also does research on the ATM gene. He continues in treatment, which has been exhausting, but as of just last month, he has reached remission… for the second time.

It was only about three months ago that I learned of the ATM connection between my daughter and my cousin. At that time, I knew it was the time for me to be tested as soon as possible. It seemed that I may provide the hereditary connection between my daughter and cousin. Nonetheless, I will have to wait until October 2025 to get an appointment to meet with a genetic counselor and then be tested.

Clearly, there is no rush with five months before I can be tested, but I began to gather genetically oriented medical records: mine and those of other family members. As I was doing that task, I reviewed my cousin’s genetic testing information and found that his second mutation was on the KRAS gene. The KRAS gene is linked to two cancers in addition to the two my cousin has faced: colorectal and lung cancer. Lung is the cancer that I fought for seven years!

Finally, after so many years, we have more knowledge. Although it’s certainly not good news, it is news, and I feel passionate about providing for the future of our family by sharing it… but my family of origin still is not close. Just because I am passionate about sharing my new knowledge and understanding doesn’t mean other family members will be.

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