MSK Study: Mesothelioma Rising in People Under 50, BAP1 Mutations a Key Factor

A retrospective study from Memorial Sloan Kettering Cancer Center, published March 18, 2026, in JCO Precision Oncology, found that mesothelioma is increasingly being diagnosed in adults under 50, many of whom carry inherited BAP1 gene mutations rather than a history of occupational asbestos exposure. The analysis of 273 younger patients challenges the long-held assumption that mesothelioma is exclusively a disease of older men who worked in industrial trades.

What the Study Found

The MSK research team examined clinical records and genomic data from 273 people diagnosed with pleural mesothelioma before age 50. The cohort included a notable proportion of women and individuals with no documented workplace asbestos exposure, a demographic profile that diverges sharply from the typical mesothelioma population.

The most striking finding involved BAP1, a tumor suppressor gene. Mutations in BAP1 were present in more than half of the tumors analyzed. While BAP1 mutations are found in many mesothelioma tumors regardless of age, the inherited (germline) form appeared at higher rates in the younger cohort.

A small but significant subset of patients had hereditary BAP1 mutations that predisposed them to mesothelioma independently of asbestos.

Other risk factors identified in younger patients included prior chest radiation, such as treatment for Hodgkin lymphoma, and family histories of cancers associated with BAP1 tumor predisposition syndrome, including uveal melanoma and renal cell carcinoma.

Why Age Matters for Treatment

The distinction between younger and older patients with mesothelioma is not merely demographic. It has direct implications for treatment strategy.

Younger patients tend to have better baseline health, which can make them candidates for more aggressive multimodal treatment approaches combining surgery, chemotherapy, and radiation. Those with specific genetic profiles may also be eligible for targeted therapies and clinical trials designed around molecular vulnerabilities.

MSK noted that its multidisciplinary teams, which meet biweekly to review individual cases, draw on one of the world’s largest mesothelioma databases to personalize treatment plans. The center emphasized that early diagnosis at a specialized facility preserves the widest range of treatment options, particularly access to clinical trials.

Since 2000, only two new FDA-approved therapies for mesothelioma have reached the market. Each extends survival by a matter of months, underscoring the importance of ongoing research and trial participation.

The Genetic Factor

The role of BAP1 mutations in mesothelioma has been an area of growing research. The gene normally functions as a tumor suppressor, and when it is inactivated through mutation, cells lose a critical brake on uncontrolled growth.

For families with inherited BAP1 mutations, the implications extend beyond the individual patient. Relatives may carry the same mutation and face elevated cancer risk, including mesothelioma, even without asbestos exposure. Genetic testing and counseling can identify at-risk family members, though researchers have noted that fear of litigation has in some cases discouraged families from pursuing testing.

The MSK study reinforces calls for broader genetic screening in mesothelioma cases, particularly when patients are diagnosed at younger ages or lack clear exposure histories.

A Shifting Profile

The traditional profile of a person with mesothelioma, a man over 70 with decades of industrial asbestos exposure, remains the most common presentation. The average age at diagnosis is between 70 and 75, and approximately 85% of cases occur in men.

But the MSK data adds to evidence that this profile is not universal. Between 2,000 and 3,300 new mesothelioma cases are diagnosed in the United States each year, and a meaningful fraction involve people who fall outside the expected demographic.

Rising awareness of non-occupational exposure pathways, including secondary exposure through contaminated clothing and naturally occurring asbestos in soil, has expanded the understanding of who is at risk.

For families dealing with a mesothelioma diagnosis in someone under 50, the MSK findings suggest that genetic evaluation should be part of the clinical workup, both for treatment planning and for assessing risk to other family members.