Based on the academic centres included in this study, TGCT is rarely diagnosed among BA males in Cape Town, South Africa. Over our 15-year study period, there were only 5 BA males within the entire cohort (ranging from 0 to 2 individuals in any given year). Our results are consistent with the reportedly low incidence among native African males in southwestern Nigeria (26 cases of testicular and para-testicular tumors over the 17 year period of 1989 to 2005, 8 of which were TGCT; average incidence of 1.5 cases per year; 0.55 per 100,000 population) [4]. Our data is also in line with that from the National Cancer Registry, which reports annual incidence rates for cancer cases diagnosed in both public and private pathology laboratories throughout South Africa. The age standardized incidence rate per 100,000 for black males was the same in 2012 as it was in 2000 (0.17) [5, 6].
The relatively rare and stably low incidence of TGCT among BA males appears to contrast the trend of increasing incidence among AA males [3]. In our study, it was noted that the overall number of BA patients admitted to both centres during the study period increased, yet the number of BA patients with TGCT remained relatively low (Fig. 2). The number of Caucasian admissions remained stable, but there was an increase in the number of Caucasian patients presenting with TGCT. This data is difficult to interpret, however, as it is not necessarily representative of the whole country.
Although the disease is more commonly encountered among non-Hispanic Caucasian males relative to AA in the US, the incidence increased nearly 40% over 15 years in the latter population [3]. In fact, the incidence of testicular cancer has increased in most populations worldwide based on data comparisons from the early 1970s to the late 2000s, with the highest values observed in Europe and North America, and the lowest in Asia and Africa [7]. Reasons for the rise are largely unclear, but it may represent a combination of environmental and genetic factors. A Danish study found that risk of developing testis cancer was lower for first-generation citizens compared to those of longer lineage [8]. However, the risk discrepancy faded by second-generation birth. These findings support a theory of environmental influence. In addition to a rising incidence, AA males diagnosed with testicular cancer have significantly worse 5- and 10-year overall survival. Studies conflict as to whether the survival difference disappears when adjusting for stage at presentation [9,10,11].
In terms of stage at presentation (Fig. 3), there is a bimodal peak, whereby patients tend to present with very low or very high stage disease. Patients in the BA group appear to present at a higher stage of disease. Due to the low participant numbers, however, it is difficult to draw any statistically significant conclusions from this data. This does appear to be similar to the results of a study in Tanzania by Chalya et al., where 25% presented with Stage 3 disease and 39.3% presented at Stage 4 [12].
This difference in TGCT between AA and BA males may also be due to how males racially self-identify. MA and BA admissions for males and females for all reasons comprised 59.6% and 26.4% of total admissions over the 15-year study period, respectively. It is possible that many of these patients in SA who self-identify as MA would be classified as AA in the US and, therefore, we may overestimate TGCT diagnosis in AA, when a percentage of these males may be MA.
This study is not without limitations, including the retrospective design and potential for incomplete records, as well as the small sample size. Our data collection was limited to the largest two state-run hospitals in the Western Cape, thus failing to account for more affluent patients seen completely within the private sector. However, because BAs in SA are typically of lower income, our analysis is less likely to underreport the incidence in this demographic [13, 14]. The self-reported income status of all patients presenting to the two academic centres in Cape Town confirms that in our study population, patients fall into the lower income bracket of the country. The incidence was calculated based on the population at risk presenting to the two hospitals during the study period. This calculation therefore does not necessarily represent the incidence for the country.
