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Background: Testicular cancer is rare but is notable because it affects mainly young men. The incidence of this disease has been increasing in developed countries throughout the world for several decades. The authors examined trends in the incidence of testicular germ cell cancer in Ontario for the period 1964-1996 according to the 2 main histologic groups, seminoma and non-seminoma., Methods: Data on incident cases of testicular germ cell cancer diagnosed in Ontario residents aged 15-59 years between 1964 and 1996 were extracted from the population-based Ontario Cancer Registry. Annual rates of testicular cancer for the 2 histologic groups were analysed by means of log-linear regression to estimate average annual percent change., Results: Between 1964 and 1996 the incidence of testicular germ cell cancer increased by 59.4%, from 4.01 to 6.39 per 100,000. This corresponded to an average annual increase of about 2% for both nonseminoma and seminoma. The relative increase in incidence was greatest in the lowest age group (15-29 years) for both histologic groups, although the data suggest that the incidence of nonseminoma cancer in this age group began to decline in the early 1990s. The increase in incidence appears to be due to a birth cohort effect, with more recent cohorts of men at increased risk., Interpretation: The rise in the incidence of testicular germ cell cancer, not only in Ontario but also in many developed countries, requires investigation. The search for explanatory factors should focus on exposures whose prevalence may have increased over the past few decades and that are common enough to affect population incidence. The similarity of trends for seminoma and nonseminoma cancer suggests that the underlying risk factors are likely the same.

Objective: To determine which host characteristics are risk factors for cutaneous malignant melanoma in order to aim prevention and early detection programs at people at high risk., Design: Case-control study., Setting: Southern Ontario., Subjects: The 583 case subjects were aged 20 to 69 years and had had malignant melanoma newly diagnosed between Oct. 1, 1984, and Sept. 30, 1986. The 608 control subjects were randomly selected from a list of residents in the study area and were stratum matched for age, sex and municipality., Intervention: Through in-person interviews the interviewer ascertained exposure to putative external risk factors and assessed skin colour and number of nevi on the arm, and the subject reported his or her natural hair colour at age 20 years, eye colour, skin reaction to repeated sun exposure, and freckle and whole-body nevus densities., Results: Although all the host factors mentioned were significantly associated with melanoma risk when considered separately, only hair colour, skin reaction to repeated sun exposure, and self-reported freckle and nevus densities remained significant after backward logistic regression analysis. The odds ratio for melanoma was estimated to be 10.7 in people who had many nevi compared with those who had none (95% confidence interval [CI] 6.6 to 17.4), 4.0 in people who had red hair compared with those who had black hair (95% CI 1.9 to 8.2), 1.9 in people who had many freckles compared with those who had none or few (95% CI 1.3 to 2.8) and 1.4 respectively in people who burned and had a subsequent increase in tan and those who burned and had no increase in tan after repeated sun exposure compared with those who did not burn [corrected]., Conclusions: Four risk factors for malignant melanoma have been identified. Prospective evaluation of their predictive value should be done. In the meantime, however, these factors should be used to identify people apparently at high risk for malignant melanoma, who can then be targeted for early detection and prevention programs.

In a retrospective case-control study biopsy specimens of cervical intraepithelial neoplasia (CIN) lesions from 47 women in whom invasive cancer subsequently developed (cases) and from 94 control subjects in whom CIN was diagnosed within 6 months of the diagnosis for the matched case subject but invasive disease did not develop were tested for human papillomavirus (HPV) DNA with tissue in-situ hybridization. There were no significant differences in the frequency of detection of HPV DNA between the two groups. In a cross-sectional survey the prevalence of HPV DNA was found to be 11% in specimens without CIN, 27% in those with CIN I, 49% in those with CIN II and 56% in those with CIN III. The positivity rates for HPV 16/33 DNA increased with the severity of CIN, but this was not observed for HPV 6/11 and 18 DNA. A comparison of the results of the case-control and cross-sectional studies suggested that the younger cohort of women had higher prevalence rates of HPV DNA than the older cohort.

In 1977 the rate of death from testicular cancer in Ontario began to decline following a long period of relative stability. This coincided with the addition of cisplatin to the chemotherapeutic regimens used in the treatment of disseminated germ-cell testicular cancer. A study was carried out to determine whether the decline has been similar for the two major histologic subgroups, seminoma and nonseminoma. By means of Ontario Cancer Registry data, histologic type was determined for all testicular cancers causing death in Ontario residents between 1964 and 1982, and death rates were calculated for seminoma and nonseminoma germ-cell testicular cancer. The rates of death from nonseminoma exceeded those from seminoma for the entire study period. Although the death rates for both subgroups declined by about 50% after 1976, the reduction in the overall rate of death from testicular cancer is primarily attributable to the decline in the rate for nonseminoma germ-cell testicular cancer. The increased overall rate of death from testicular cancer (all types) between 1980 and 1984 is cause for concern and indicates the need for continued monitoring of the trends in rates of death from this disease.