Cancer disparities for LGBTQ+ patients identified more fully

It has been widely reported that patients who identify as LGBTQ+ (lesbian, gay, bisexual, transgender, queer, or other gender-diverse characteristic) have more health risks than the cisgender and/or heterosexual population. According to previous studies, most of the disparity has been attributed to the minority stress theory: Members of these communities disproportionally experience discrimination, and this results in mistrust in medical settings—further increasing stress.

Regarding cancer specifically, these society-derived stressors have been reported to lead to lower rates of timely screening, higher rates of infection with cancer-causing viruses, and higher rates of health risk behaviors—increasing the potential risk for various cancers in the LGBTQ+ community. Another issue builds on the aforementioned minority stress theory, which can result in avoidance because of the fear that a health care provider will refuse to care for them. Importantly, the LGBTQ+ communities are diverse, and cancer incidences may differ within specific gender identities and/or sexual orientations (SOs). Because of insufficient details from previous studies, accurate data regarding cancer incidence in specific groups have been lacking.

A study appearing in Cancer (doi: 10.1002/cncr.35356) adds new evidence of the disproportional cancer burden faced by sexual minoritized people. Study author Aimee K. Huang, MD, MPH, a junior faculty member at Massachusetts General Hospital and Harvard Medical School in Boston, Massachusetts, says that most prior studies relied on indirect approximations of incidence and prevalence. “However, for studies that were able to directly measure incidence, the scopes of their investigations were often limited to the most common cancers, unidimensional SO measurements, or had other methodological challenges due to data limitations,” she says.

For the study, researchers culled SO and cancer diagnosis data (from 1989 to 2017) from the Nurses’ Health Study II (NHSII), a longitudinal cohort of 101,543 nurses across the United States. The mean ages and race/ethnicity compositions were similar across all the groups.

The primary outcome was the self-disclosed and electronic health record–verified incidences of cancer among four different sexual minority groups: heterosexual with a past same-sex attraction/behavior/identity (n = 5034), mostly heterosexual (n = 1825), bisexual (n = 394), and lesbian (n = 996). These groups were compared to a “reference” group that self-identified as lifelong heterosexual (n = 93,294). The researchers also determined the case numbers, incidence rates, and age-adjusted incidence rate ratios (aIRRs) of 21 site-specific cancers for each group. Using aIRRs, they compared incidence rates between the reference group and the four SO subgroups.

The researchers reported that the cancer incidence rate (cases per 100,000 person-years) was highest for those who self-described as lesbian (516). Participants in the reference group had an incidence of 428, which was slightly lower than for heterosexual women with past same-sex attractions/partners/identity (449) and the mostly heterosexual cohort (439). Those who self-described as bisexual constituted the smallest cohort, and the researchers did not feel that an accurate conclusion could be reached. They found that lesbian people were approximately twice as likely to be diagnosed with three types of cancer: thyroid cancer (aIRR, 1.87), basal cell carcinoma (aIRR, 1.85), and non-Hodgkin lymphoma (aIRR, 2.13).

The study found sexual minority women to have a lower risk of lung cancer diagnosis despite earlier studies that reported higher prevalences of smoking and lung cancer among these groups. The study also found no lung cancer cases among lesbians and found heterosexual women with a prior same-sex history to have a lower incidence of lung cancer. The study authors believe that these findings in the NHSII cohort might be due to lower rates of smoking in this nursing population versus the general public. “As such, our finding of a lower lung cancer incidence in sexual minority women with low case numbers should be interpreted with caution,” they wrote. (For more details on the prevalence of each cancer type in each of the five groups, see Table 2 in the study.)

Chunkit Fung, MD, associate chair of diversity, equity, and inclusion in the Department of Medicine of the University of Rochester in Rochester, New York, says that this large US longitudinal study is important because of its detailed report showing that sexual minority women have higher all-cancer incidence than heterosexual women. He says that one finding of particular importance is the determination that lesbian women are most disproportionately burdened by cancer.

“This study highlights the importance for future research to understand how different cancer risk factors, social determinants of health, and stigma/discrimination affecting LGBTQ+ communities may lead to higher cancer incidences among sexual and gender minorities,” Dr Fung adds.

Dr Huang says that there are many aspects to the study that need to be emphasized. First, the importance of measuring cancer incidence versus prevalence. Dr Huang points out that although both incidence and prevalence are important metrics in cancer epidemiology, incidence studies are particularly crucial for understanding factors associated with increased cancer rates, assessing the effectiveness of prevention programs, and guiding resource allocation for early detection and prevention efforts. “Assessments of cancer prevalence provide valuable information about the overall burden of cancer and survivorship but are less useful for identifying new cases and trends in disease occurrence. By focusing on cancer incidence, our study is better positioned to assess true risk and the role and impact inclusive early detection and prevention strategies may have among sexual minoritized populations,” she says.

Dr Huang notes that few health data infrastructures systematically collect SO and oncological data, and the ones that do tend to have broad categorizations that lack nuances (heterosexual vs. sexual minority or heterosexual vs. gay/lesbian and bisexual). “Our study includes a comprehensive measurement of SO, encompassing lifetime attraction, behavior, and identity. Such detailed categorization allows for a more nuanced understanding of how different cancer risks and incidences might present in different sexual minoritized groups.”

Dr Huang adds, “This also allows us to capture sexual minority individuals who may not typically be captured in other studies, such as people who identify as heterosexual but disclosed same-sex attraction or partnerships in their lifetime.”

Dr Huang says that another key point is the study’s assessment of 21 cancer types, whereas previous studies focused on narrower ranges of cancer types. She says that besides the significantly higher incidences of thyroid cancer, basal cell carcinoma, and non-Hodgkin lymphoma among lesbian women, although incidence rates at other sites did not reach statistical significance, a pattern of higher incidence rates was seen across the board for lesbian women. “This trend was reflected in a statistically significant increase in the overall cancer incidence among lesbian women in our sensitivity analysis.”

This may suggest, says Dr Huang, that beyond individual-level risk factors and risk factors specific to certain cancer sites, there may be structural-level risk factors at play that are adversely affecting cancer risks among sexual minoritized populations. “Therefore, inclusive measures should extend beyond guidelines and practices for specific cancers with existing screening programs into more inclusive medical practices and healthcare policies. This would help to tackle structural risk factors such as stigma and heterosexism that may have contributed to this disproportional cancer burden we saw in this cohort.”

According to Dr Huang, the research team believes that the key takeaway for cancer researchers and clinicians is the importance of recognizing and addressing the unique cancer risks and needs of sexual minority populations. “There is a critical need for more inclusive research and tailored healthcare interventions to close gaps in cancer prevention and improve overall cancer care and outcomes for these communities. Increased awareness and sensitivity to these issues can enhance patient education, patient-provider communication, and the effectiveness of cancer prevention and treatment strategies.”

Dr Fung agrees. “It is imperative that both clinicians and researchers collect comprehensive and standardized sexual orientation data in their clinic and research programs to quantify and understand sexual orientation-related health disparities.”