Cohort profile: the South African HIV Cancer Match (SAM) Study, a national population-based cohort

HIV-1 Viremia and Cancer Risk in 2.8 Million People: the South African HIV Cancer Match Study

BACKGROUND

Most research on HIV-1 viremia and cancer risk is from high-income countries. We evaluated the association between HIV-1 viremia and the risk of various cancer types among people with HIV (PWH) in South Africa.

METHODS

We analysed data from the South African HIV Cancer Match study, based on laboratory measurements from the National Health Laboratory Services and cancer records from the National Cancer Registry from 2004-2014. Using Cox proportional hazards models, we estimated hazard ratios (HR) for cancer incidence per unit increase in time-updated Log10 HIV-1 RNA viral load copies/mL. We created partially adjusted (sex, age, calendar year) and fully adjusted models (additionally including time-updated CD4 count).

RESULTS

We included 2,770,200 PWH with 10,175 incident cancers; most common were cervical cancer (N=2,481), Kaposi sarcoma (N=1,902), breast cancer (N=1,063), and non-Hodgkin lymphoma (N=863). Hazard ratios for the association of HIV-1 viremia and cancer risk changed after partial and full adjustment and were generally attenuated for infection-related cancers but tended to increase for infection-unrelated cancers. In the fully adjusted model, HIV-1 viremia was associated with an increased risk of Kaposi sarcoma (HR per unit increase in Log10 HIV-1 RNA viral load: 1.38, 95% CI 1.35-1.42), leukemia (HR: 1.28, 95% CI 1.13-1.45), non-Hodgkin lymphoma (HR: 1.24, 95% CI 1.19-1.29), conjunctival cancer (HR: 1.19, 95% CI 1.11-1.25), and colorectal cancer (HR: 1.11, 95% CI 1.02-1.21). Associations with other cancer types were weaker or absent.

CONCLUSIONS

Our findings underline the importance of sustained viral suppression for cancer prevention among PWH in South Africa.

State of the science and future directions for research on HIV and cancer: Summary of a joint workshop sponsored by IARC and NCI

An estimated 38 million people live with human immunodeficiency virus (HIV) worldwide and are at excess risk for multiple cancer types. Elevated cancer risks in people living with HIV (PLWH) are driven primarily by increased exposure to carcinogens, most notably oncogenic viruses acquired through shared transmission routes, plus acceleration of viral carcinogenesis by HIV-related immunosuppression. In the era of widespread antiretroviral therapy (ART), life expectancy of PLWH has increased, with cancer now a leading cause of co-morbidity and death. Furthermore, the types of cancers occurring among PLWH are shifting over time and vary in their relative burden in different parts of the world. In this context, the International Agency for Research on Cancer (IARC) and the US National Cancer Institute (NCI) convened a meeting in September 2022 of multinational and multidisciplinary experts to focus on cancer in PLWH. This report summarizes the proceedings, including a review of the state of the science of cancer descriptive epidemiology, etiology, molecular tumor characterization, primary and secondary prevention, treatment disparities and survival in PLWH around the world. A consensus of key research priorities and recommendations in these domains is also presented.

Incidence and epidemiology of conjunctival squamous cell carcinoma in relation to the HIV epidemic in South Africa: a 25-year analysis of the National Cancer Registry (1994-2018)

AIMS

To describe the incidence and epidemiology of conjunctival squamous cell carcinoma (CSCC) in South Africa over a 25-year period (1994-2018), with particular reference to the HIV epidemic.

METHODS

Incident cases of histologically diagnosed CSCC were identified from the pathology-based South African National Cancer Registry. Crude and direct age-standardised incidence rates (ASIRs) per 100 000 persons (Segi World Standard Population) were calculated using national population statistics and compared by age, sex and ethnicity. Trends in the incidence and demographic features of CSCC were described and analysed. Incidence rates were compared with national HIV-related statistics for the same time period.

RESULTS

In total, there were 9016 reported CSCC cases (women: 56.6%, black: 86.8%, mean age: 41.5 years). The overall ASIR was 0.78 per 100 000. Two distinct epidemiological patterns were identified: (1) older white men, and (2) younger black women. There was a sixfold increase in CSCC incidence rates between 1994 and 2009 with a corresponding shift from the first to the second disease profile. Despite rising HIV seroprevalence, CSCC incidence rates have declined since 2009. A strong ecological correlation (r=0.96) between CSCC incidence and widespread antiretroviral therapy (ART) provision was identified.

CONCLUSION

This study highlights the evolving trends and disease burden of CSCC in South Africa. Widespread ART provision is ecologically correlated with declining CSCC rates over the last decade. These findings are in keeping with reported trends for other HIV-related cancers and have important implications for future incidence studies and public health policy.

Gynaecologic and breast cancers in women living with HIV in South Africa: A record linkage study

Breast and gynaecologic cancers account for approximately half of all cancers diagnosed amongst women in South Africa, many of whom also live with HIV. We aimed to determine the incidence of and risk factors for developing breast and gynaecologic cancers in women living with HIV (WLHIV) in South Africa. This is a longitudinal analysis of the South African HIV Cancer Match study including women aged ≥15 years with two or more HIV-related laboratory tests. We used Cox proportional hazard models to determine the association of Human Papilloma Virus (HPV)-related and hormone-related gynaecologic cancer with patient- and municipal-level characteristics. From 3 447 908 women and 10.5 million years of follow-up, we identified 11 384 incident and 7612 prevalent gynaecologic and breast cancers. The overall crude incidence rate was 108/1 00 000 person-years (pyears) (95% confidence interval [CI]: 106-110), with the highest incidence observed for cervical cancer (70/1 00 000 pyears; 95% CI: 68.5-71.7). Low CD4 cell counts and high HIV RNA viral loads increased the risk of cervical and other HPV-related cancers. Age was associated with both HPV-related and hormone-related cancers. Women accessing health facilities in high socioeconomic position (SEP) municipalities were more likely to be diagnosed with HPV-related cancers and breast cancer than women accessing care in low SEP municipalities. It is important to improve the immunologic status of WLHIV as part of cancer prevention strategies in WLHIV. Cancer prevention and early detection programmes should be tailored to the needs of women ageing with HIV. In addition, SEP disparities in cancer diagnostic services have to be addressed.

Decreasing incidence of conjunctival squamous cell carcinoma in people with HIV in South Africa

BACKGROUND

The main risk factors for squamous cell carcinoma of the conjunctiva (SCCC) are immunodeficiency and exposure to ultraviolet radiation. Little is known about SCCC epidemiology among people with HIV (PWH) in South Africa.

METHODS

We used data from the South African HIV Cancer Match study, a nation-wide cohort of PWH in South Africa, created through a privacy-preserving probabilistic record linkage of HIV-related laboratory records from the National Health Laboratory Service and cancer records from the National Cancer Registry from 2004 to 2014. We calculated crude incidence rates, analyzed trends using joinpoint models, and estimated hazard ratios for different risk factors using Royston-Parmar flexible parametric survival models.

RESULTS

Among 5 247 968 PWH, 1059 cases of incident SCCC were diagnosed, for a crude overall SCCC incidence rate of 6.8 per 100 000 person-years. The SCCC incidence rate decreased between 2004 and 2014, with an annual percentage change of ‒10.9% (95% confidence interval: ‒13.3 to ‒8.3). PWH residing within latitudes 30°S to 34°S had a 49% lower SCCC risk than those residing at less than 25°S latitude (adjusted hazard ratio = 0.67; 95% confidence interval: 0.55 to 0.82). Other risk factors for SCCC were lower CD4 counts and middle age. There was no evidence for an association of sex or settlement type with SCCC risk.

CONCLUSIONS

An increased risk of developing SCCC was associated with lower CD4 counts and residence closer to the equator, indicative of higher ultraviolet radiation exposure. Clinicians and PWH should be educated on known SCCC preventive measures, such as maintaining high CD4 counts and protection from ultraviolet radiation through sunglasses and sunhats when outdoors.

Age and Cancer Incidence in 5.2 Million People With Human Immunodeficiency Virus (HIV): The South African HIV Cancer Match Study

BACKGROUND

Old age is an important risk factor for developing cancer, but few data exist on this association in people with human immunodeficiency virus (HIV, PWH) in sub-Saharan Africa.

METHODS

The South African HIV Cancer Match study is a nationwide cohort of PWH based on a linkage between HIV-related laboratory records from the National Health Laboratory Service and cancer diagnoses from the National Cancer Registry for 2004-2014. We included PWH who had HIV-related tests on separate days. Using natural splines, we modeled cancer incidence rates as a function of age.

RESULTS

We included 5 222 827 PWH with 29 580 incident cancer diagnoses-most commonly cervical cancer (n = 7418), Kaposi sarcoma (n = 6380), and breast cancer (n = 2748). In young PWH, the incidence rates for infection-related cancers were substantially higher than for infection-unrelated cancers. At age 40 years, the most frequent cancer was cervical cancer in female and Kaposi sarcoma in male PWH. Thereafter, the rates of infection-unrelated cancers increased steeply, particularly among male PWH, where prostate cancer became the most frequent cancer type at older age. Whereas Kaposi sarcoma rates peaked at 34 years (101/100 000 person-years) in male PWH, cervical cancer remained the most frequent cancer among older female PWH.

CONCLUSIONS

Infection-related cancers are common in PWH in South Africa, but rates of infection-unrelated cancers overtook those of infection-related cancers after age 54 years in the overall study population. As PWH in South Africa live longer, prevention and early detection of infection-unrelated cancers becomes increasingly important. Meanwhile, control strategies for infection-related cancers, especially cervical cancer, remain essential.