BACKGROUND: Testicular germ cell tumor (TGCT) incidence increased steadily in recent decades, but causes remain elusive. Germ cell function may be influenced by cannabinoids, and 2 prior epidemiologic studies reported that the use of marijuana may be associated with nonseminomatous TGCT. Here, the authors evaluate the relation between TGCTs and exposure to marijuana and other recreational drugs using a population‐based case‐control study.METHODS: In total, 163 patients who were diagnosed with TGCT in Los Angeles County from December 1986 to April 1991 were enrolled, and 292 controls were matched on age, race/ethnicity, and neighborhood. Participants were asked about drug use by a structured, in‐person interview. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression analysis adjusted for history of cryptorchidism; education; religiosity; and reported use of marijuana, cocaine, and amyl nitrite.RESULTS: Compared with never use, ever use of marijuana had a 2‐fold increased risk (OR, 1.94; 95% CI, 1.02‐3.68), whereas ever use of cocaine had a negative association with TGCT (OR, 0.54; 95% CI, 0.32‐0.91). Stratification on tumor histology revealed a specific association of marijuana use with nonseminoma and mixed histology tumors (OR, 2.42; 95% CI, 1.08‐5.42).CONCLUSIONS: A specific association was observed between marijuana use and the risk of nonseminoma and mixed tumors. To the authors' knowledge, this is the first report of a negative association between cocaine use and TGCT risk. The current results warrant mechanistic studies of marijuana's effect on the endocannabinoid system and TGCT risk and caution that recreational and therapeutic use of cannabinoids by young men may confer malignant potential to testicular germ cells. Cancer 2012. © 2012 American Cancer Society.

Inherited variation at MC1R is associated with elevated melanoma risk among non-Hispanic whites (NHWs). MC1R genetic testing may unmask previously unrecognized disease risk, especially among individuals with few melanoma phenotypic risk factors. We recruited NHW individuals with limited phenotypic risk factors from two primary care clinics in west-central Florida. Participants (n = 1134) were randomized within MC1R genotype risk group (average/higher) to receive mailed precision prevention (i.e., intervention) or generic prevention materials. Participants reported hours of weekday and weekend sun exposure, frequency of intentional outdoor tanning and sun protection behaviors, number of sunburns, indoor tanning episodes, and skin examinations at baseline, and after 6 and 12 months. Among MC1R higher-risk participants, the intervention increased the likelihood of often or always wearing a shirt with sleeves (OR = 1.49, p = 0.03) and seeking shade or using an umbrella (OR = 1.42, p = 0.046), and it decreased the number of sunburns among their young children (β = −0.13, p = 0.03). Intervention effects were not noted among MC1R average-risk participants. Moderation analyses identified intervention effects within subgroups in average-risk and higher-risk participants. Precision prevention information conveying MC1R testing results can increase the practice of some sun protection behaviors among at-risk individuals with limited melanoma risk phenotypes and may provide a cross-generational tool to counteract increasing incidence of melanoma.

Purpose: Skin cancer incidence is increasing among Hispanics, who experience worse outcomes than non-Hispanic Whites. Precision prevention incorporating genetic testing for (melanocortin-1 receptor) MC1R, a skin cancer susceptibility marker, may improve prevention behavior.Experimental Design: Hispanic participants (n = 920) from Tampa, FL and Ponce, PR, were block-randomized within MC1R higher- and average-risk groups to precision prevention or generic prevention arms. We collected baseline information on demographics, family history of cancer, phenotypic characteristics, health literacy, health numeracy, and psychosocial measures. Participants reported weekday and weekend sun exposure (in hours), number of sunburns, frequency of five sun protection behaviors, intentional outdoor and indoor tanning, and skin examinations at baseline, 3 months, and 9 months. Participants also reported these outcomes for their eldest child ≤10 years old.Results: Among MC1R higher-risk participants, precision prevention increased sunscreen use (OR = 1.74, P = 0.03) and receipt of a clinical skin exam (OR = 6.51, P = 0.0006); and it decreased weekday sun exposure hours (β = −0.94, P = 0.005) and improved sun protection behaviors (β = 0.93, P = 0.02) in their children. There were no significant intervention effects among MC1R average-risk participants. The intervention did not elevate participant cancer worry. We also identified moderators of the intervention effect among both average- and higher-risk participants.Conclusions: Receipt of MC1R precision prevention materials improved some skin cancer prevention behaviors among higher-risk participants and their children and did not result in reduced prevention activities among average-risk participants. Despite these encouraging findings, levels of sun protection behaviors remained suboptimal among participants, warranting more awareness and prevention campaigns targeted to HispanicsSignificance: Our results support a precision public health approach to reducing skin cancers among Hispanics, an underserved population in precision medicine, and may additionally improve preventive behaviors among their children.

Few studies have examined cognitive responses to mailed precision prevention materials. MC1R is a robust, well-described melanoma susceptibility marker. The purpose was to assess cognitive responses to generic or precision prevention materials incorporating MC1R genetic risk. Non-Hispanic White participants (n = 1134) enrolled in a randomized controlled trial received either precision prevention materials incorporating MC1R genetic risk (higher/average) or generic prevention (standard) materials. Six months after baseline, 808 (71.3%) participants reported on the amount of prevention materials read (5-point scale); believability and clarity of materials; intention to change preventive behaviors (7-point Likert scale); and recall of their MC1R genetic risk. Comparisons were conducted using Kruskal–Wallis and chi-squared tests. Overall, participants read most to all (Mdn = 4, IQR = 2) of the prevention materials, reported high believability (Mdn = 7, IQR = 1) and clarity (Mdn = 7, IQR = 1), and moderate intention to change preventive behaviors (Mdn = 5, IQR = 2). Higher-risk participants reported slightly less clarity (Mdn = 6, IQR = 2) than either average-risk (Mdn = 6, IQR = 1, p = 2.50 × 10⁻³) or standard participants (Mdn = 7, IQR = 1, p = 2.30 × 10⁻⁵); and slightly less believability (Mdn = 6, IQR = 1) than standard participants (Mdn = 7, IQR = 1, p = .005). Higher-risk participants were 2.21 times as likely (95% CI = 1.43–3.43) to misremember or forget their risk compared to average-risk participants; misremembering was observed only among higher-risk participants (14%). Mailed precision prevention information were mostly read, highly believable and clear, and resulted in moderate levels of intention to change sun protection behaviors, bolstering the feasibility of population-level precision prevention. Defensive reactions may explain lower clarity, believability, and higher incorrect risk recall among higher-risk participants. Precision prevention uses an individual’s genetics, environment, and/or lifestyle to promote prevention behaviors. However, if materials incorporating precision prevention information are not easily accessible, individuals may misinterpret or distrust findings. Few studies have examined participant-reported believability and clarity of mailed precision prevention materials, how much they read, and whether they intend to change preventive behaviors. We assessed genetic risk for melanoma by determining DNA variation at the MC1R gene, a known melanoma risk marker. Participants were mailed either precision prevention materials conveying their MC1R genetic risk or generic (without genetic risk information) prevention materials. Overall, participants read most of the materials, gave high believability and clarity scores, and reported moderate levels of intention to change preventive behavior. However, participants at higher genetic risk had slightly lower believability and clarity scores than the generic group and were more likely to forget or misremember their genetic risk than participants at average genetic risk. Among participants who correctly recalled their genetic risk, differences in believability diminished, while differences in clarity remained. We conclude that precision prevention materials are highly believable and clear, but additional strategies may be necessary to maximize believability, clarity, and risk recall for individuals at a higher genetic risk.