Clonal hematopoiesis of indeterminate potential (CHIP) and mosaic chromosomal alterations (mCAs) are associated with an increased risk for breast cancer, and CHIP is associated with increased mortality in patients with colon cancer, according to the authors of new research.
These findings, drawn from almost 11,000 patients in the Women’s Health Initiative (WHI) study, add further evidence that CHIP and mCA drive solid tumor risk, alongside known associations with hematologic malignancies, reported lead author Pinkal Desai, MD, associate professor of medicine and clinical director of molecular aging at Englander Institute for Precision Medicine, Weill Cornell Medical College, New York City, and colleagues.
How This Study Differs From Others of Breast Cancer Risk Factors
“The independent effect of CHIP and mCA on risk and mortality from solid tumors has not been elucidated due to lack of detailed data on mortality outcomes and risk factors,” the investigators wrote in Cancer, although some previous studies have suggested a link.
In particular, the investigators highlighted a 2022 UK Biobank study, which reported an association between CHIP and lung cancer and a borderline association with breast cancer that did not quite reach statistical significance.
But the UK Biobank study was confined to a UK population, Dr. Desai noted in an interview, and the data were less detailed than those in the present investigation.
“In terms of risk, the part that was lacking in previous studies was a comprehensive assessment of risk factors that increase risk for all these cancers,” Dr. Desai said. “For example, for breast cancer, we had very detailed data on [participants’] Gail risk score, which is known to impact breast cancer risk. We also had mammogram data and colonoscopy data.”
In an accompanying editorial, Koichi Takahashi, MD, PhD , and Nehali Shah, BS, of The University of Texas MD Anderson Cancer Center, Houston, Texas, pointed out the same UK Biobank findings, then noted that CHIP has also been linked with worse overall survival in unselected cancer patients. Still, they wrote, “the impact of CH on cancer risk and mortality remains controversial due to conflicting data and context‐dependent effects,” necessitating studies like this one by Dr. Desai and colleagues.
How Was the Relationship Between CHIP, MCA, and Solid Tumor Risk Assessed?
To explore possible associations between CHIP, mCA, and solid tumors, the investigators analyzed whole genome sequencing data from 10,866 women in the WHI, a multi-study program that began in 1992 and involved 161,808 women in both observational and clinical trial cohorts.
In 2002, the first big data release from the WHI suggested that hormone replacement therapy (HRT) increased breast cancer risk, leading to widespread reduction in HRT use.
More recent reports continue to shape our understanding of these risks, suggesting differences across cancer types. For breast cancer, the WHI data suggested that HRT-associated risk was largely driven by formulations involving progesterone and estrogen, whereas estrogen-only formulations, now more common, are generally considered to present an acceptable risk profile for suitable patients.
The new study accounted for this potential HRT-associated risk, including by adjusting for patients who received HRT, type of HRT received, and duration of HRT received. According to Desai, this approach is commonly used when analyzing data from the WHI, nullifying concerns about the potentially deleterious effects of the hormones used in the study.
“Our question was not ‘does HRT cause cancer?’ ” Dr. Desai said in an interview. “But HRT can be linked to breast cancer risk and has a potential to be a confounder, and hence the above methodology.
“So I can say that the confounding/effect modification that HRT would have contributed to in the relationship between exposure (CH and mCA) and outcome (cancer) is well adjusted for as described above. This is standard in WHI analyses,” she continued.
“Every Women’s Health Initiative analysis that comes out — not just for our study — uses a standard method ... where you account for hormonal therapy,” Dr. Desai added, again noting that many other potential risk factors were considered, enabling a “detailed, robust” analysis.
Dr. Takahashi and Ms. Shah agreed. “A notable strength of this study is its adjustment for many confounding factors,” they wrote. “The cohort’s well‐annotated data on other known cancer risk factors allowed for a robust assessment of CH’s independent risk.”