In recent years, the incidence of oral tongue cancer has increased significantly among young, white adults in the United States. However, the reasons for this increase are unknown. In a study published online April 12 in Cancer, researchers examined the risk of developing oral tongue cancer and other head and neck cancers in 2 immunosuppressed populations: recipients of solid organ transplants and people with HIV. The researchers hypothesized that a virus may cause oral tongue cancer; consequently, immunosuppressed populations would be expected to be at an elevated risk.
The authors collected data from the ongoing Transplant Cancer Match (TCM) study and the HIV/AIDS Cancer Match (HACM) study. These studies link population-based cancer registries with the US Scientific Registry of Transplant Recipients or state HIV registries.
Study participants consisted of 242,022 transplant recipients and 465,429 people with HIV. Most transplant recipients in the TCM group were male (61%), white (61%), and younger than 50 years (53%) at the time of surgery. The kidney was the most commonly transplanted organ. In the HACM study, 52% of participants had received a diagnosis of AIDS at the start of follow-up. A large proportion of HACM participants were male (72%), African American (50%), and younger than 50 years at study entry (82%). The largest proportion of participants (33%) in the HIV risk group were men who have sex with men (MSM).
Among transplant recipients, the researchers observed 36 oral tongue squamous cell carcinomas (SCCs), 203 oropharyngeal SCCs, 86 other oral cavity SCCs, and 48 non-Hodgkin lymphomas of the oral cavity/pharynx. Compared with the general US population, the incidence of all specified head and neck cancers was significantly elevated in this group.
In the group of people with HIV, the authors observed 70 oral tongue SCCs, 311 oropharyngeal SCCs, 117 oral cavity SCCs, and 144 oral cavity/pharynx non-Hodgkin lymphomas. The incidence of all specified head and neck cancers also was significantly elevated among people in this group.
The study results showed that the risk of oral tongue SCC among transplant recipients was similar across sex and race, and it increased with age and the time since transplantation. However, the risk of other specified head and neck cancers was significantly higher among men and whites in this group. The authors did not observe any significant difference in cancer risk according to use of specific immunosuppressive drugs or human leukocyte antigen–mismatch status.
Among participants with HIV, the risk of oral tongue SCC was similar in men and women; however, the risk was higher among whites and increased with age and time since AIDS onset. The researchers also observed a significantly higher risk of developing oral tongue SCC among MSM than among other HIV groups (incidence rate ratio, 2.0; 95% confidence interval, 1.2 to 3.4). In this study, nearly one-half of oral tongue SCCs (n = 34) among people with HIV occurred in the MSM group.
The risk of oral tongue, other oral cavity, and oropharyngeal SCCs was modestly elevated among people with immunosuppression compared with the general US population, the authors wrote. Thus, the study findings suggest that the “etiology underlying oral tongue SCC, similar to that of oropharyngeal and other oral cavity SCCs, is not greatly impacted by immunosuppression.” However, there appears to be a subtle role for chronic long-term immunosuppression, as the incidence of head and neck cancers increased over time in the study populations.
The authors concluded that the elevated risk of oral tongue cancer among MSM with HIV and the time since AIDS onset suggest that a sexually transmitted virus could be a cause. However, additional studies are needed to evaluate the risk factors that may be contributing to the apparent rise in oral tongue cancer in the United States.
Read the original article.