Recreational drug use and risk of Kaposi's sarcoma in HIV- and HHV-8-coinfected homosexual men

Use of poppers (nitrite inhalants) among young men who have sex with men with HIV: A clinic-based qualitative study

Nitrite inhalants (poppers) are associated with HIV transmission and commonly used among young men who have sex with men (YMSM), a group at increased risk for HIV. Significant research gaps exist in understanding the context in which YMSM use poppers. Qualitative interviews were conducted with 15 YMSM (22-31 years) with HIV to better understand the context in which poppers are used and their impacts on HIV care outcomes, such as care retention and antiretroviral adherence. The Social Ecological Model was applied to understand intrapersonal, interpersonal, community, and system level influences on popper use. Factors influencing popper use included: ubiquity of popper use in sexual settings, introduction to poppers by casual sexual partners, patient-HIV provider communication surrounding poppers, neighborhood, substance use and HIV care systems, and the legal status of poppers. Implications for clinical care, public health, policy, and future research are discussed.

Poppers Dermatitis®: A Systematic Review on a Unique Form of Contact Dermatitis® in the MSM Community

There are certain demographic characteristics that may serve as risk factors for exposure to a contact allergen. Volatile alkyl nitrites, colloquially known as "poppers," are commonly inhaled by men who have sex with men (MSM) for their psychoactive and muscle-relaxing effects. They have been reported to cause either allergic contact Dermatitis® (ACD) or irritant contact Dermatitis® (ICD), termed "poppers Dermatitis®." We searched PubMed, Embase, and Web of Science to understand the patient population, clinical presentation, diagnosis, and clinical course of poppers Dermatitis®. Our search returned 13 articles detailing 18 patients total. Most patient cases were male (n = 13/15; 87%), of whom 5 were MSM. The reports on the remaining 8 men did not disclose their sexual behaviors. The chemicals deemed responsible for adverse cutaneous side effects included amyl nitrite (6/18; 33%), butyl nitrite (3/18; 167%), isobutyl nitrite (2/18; 11%), and an unspecified alkyl nitrite (7/18, 39%). The most common diagnosis was ICD (10/18; 56%). Only 3 patients underwent alkyl nitrite patch testing, with 2 testing positive for ACD. The most commonly involved anatomic sites were perinasal (13/18; 72%) and perioral regions (10/18; 56%). Rash morphology has been described as yellow crusting, impetigo-like, eczematous, vesicular, edematous, and erythematous. Ulceration can occur with direct skin contact to concentrated nitrite solution. Poppers Dermatitis® was often self-limited with complete resolution. Dermatologists should consider poppers Dermatitis® in those presenting with a characteristic midfacial rash, especially in MSM.

Harnessing Redox Disruption to Treat Human Herpesvirus 8 (HHV-8) Related Malignancies

Reprogrammed metabolism is regarded as a hallmark of cancer and offers a selective advantage to tumor cells during carcinogenesis. The redox equilibrium is necessary for growth, spread and the antioxidant pathways are boosted following Reactive Oxygen Species (ROS) production to prevent cell damage in tumor cells. Human herpesvirus 8 (HHV-8), the etiologic agent of Kaposi sarcoma KS and primary effusion lymphoma (PEL), is an oncogenic virus that disrupts cell survival-related molecular signaling pathways leading to immune host evasion, cells growths, angiogenesis and inflammatory tumor-environment. We recently reported that primaquine diphosphate causes cell death by apoptosis in HHV-8 infected PEL cell lines in vivo and exhibits therapeutic anti-tumor activity in mice models and advanced KS. Our findings also suggest that the primaquine-induced apoptosis in PEL cells is mostly influenced by ROS production and targeting the redox balance could be a new approach to treat HHV-8 related diseases. In this review, we summarized the knowledge about the influence of ROS in cancer development; more specifically, the proof of evidence from our work and from the literature that redox pathways are important for the development of HHV-8 pathologies.

Scoping Review and Meta-Analysis Suggests that Cannabis Use May Reduce Cancer Risk in the United States

Introduction: Cannabis smoke contains carcinogens similar to tobacco, in addition to compounds with antitumor activity. Cannabis use reduces the risk of obesity and cannabinoids inhibit chronic inflammation, known causes of cancer. The net effect of Cannabis use on cancer risk is not known. Objective: To examine the association between Cannabis use and cancer risk in the United States. Methods: Identify and analyze published data on cancer risk in Cannabis users. Results: A total of 55 data points, consisting of risk ratios of cancer in Cannabis users and nonusers, were identified from 34 studies. Of these, 5 did not contain data essential for inclusion in the meta-analysis. The remaining data showed a nonsignificant trend to an association with reduced risk (relative risk [RR]=0.90, p>0.06, N=50) although heterogeneity is high (I²=72.4%). Removal of data with high risk of selection bias (defined as those from North Africa and those that failed to adjust for tobacco) and data with high risk of performance bias (defined as those with fewer than 20 cases or controls among Cannabis users) resulted in an RR <1.0 (RR=0.86, p<0.017, N=24) and large effect size (Hedges g=0.66), but did not decrease heterogeneity (I²=74.9). Of all cancer sites, only testicular cancer showed an RR value >1, although this was not significant and had a negligible effect size (RR=1.12, p=0.3, Hedges g=0.02). Following removal of testicular cancers the remaining data showed a decrease in risk (RR=0.87, p<0.025, N=41). Cancers of the head and neck showed a negative association with cancer risk (RR=0.83, p<0.05), with a large effect size (Hedges g=0.55), but high heterogeneity (I²=79.2%). RR did not reach statistical significance in the remaining cancer site categories (lung, testicular, obesity-associated, other). The data are consistent with a negative association between Cannabis use and nontesticular cancer, but there is low confidence in this result due to high heterogeneity and a paucity of data for many cancer types.

Association Between Marijuana Use and Risk of Cancer: A Systematic Review and Meta-analysis

Importance

Marijuana use is common and growing in the United States amid a trend toward legalization. Exposure to tobacco smoke is a well-described preventable cause of many cancers; the association of marijuana use with the development of cancer is not clear.

Objective

To assess the association of marijuana use with cancer development.

Data Sources

A search of PubMed, Embase, PsycINFO, MEDLINE, and the Cochrane Library was conducted on June 11, 2018, and updated on April 30, 2019. A systematic review and meta-analysis of studies published from January 1, 1973, to April 30, 2019, and references of included studies were performed, with data analyzed from January 2 through October 4, 2019.

Study Selection

English-language studies involving adult marijuana users and reporting cancer development. The search strategy contained the following 2 concepts linked together with the AND operator: marijuana OR marihuana OR tetrahydrocannabinol OR cannabinoid OR cannabis; AND cancer OR malignancy OR carcinoma OR tumor OR neoplasm.

Data Extraction and Synthesis

Two reviewers independently reviewed titles, abstracts, and full-text articles; 3 reviewers independently assessed study characteristics and graded evidence strength by consensus.

Main Outcomes and Measures

Rates of cancer in marijuana users, with ever use defined as at least 1 joint-year exposure (equivalent to 1 joint per day for 1 year), compared with nonusers. Meta-analysis was conducted if there were at least 2 studies of the same design addressing the same cancer without high risk of bias when heterogeneity was low to moderate for the following 4 cancers: lung, head and neck squamous cell carcinoma, oral squamous cell carcinoma, and testicular germ cell tumor (TGCT), with comparisons expressed as odds ratios (ORs) with 95% CIs.

Results

Twenty-five English-language studies (19 case-control, 5 cohort, and 1 cross-sectional) were included; few studies (n = 2) were at low risk of bias. In pooled analysis of case-control studies, ever use of marijuana was not associated with head and neck squamous cell carcinoma or oral cancer. In pooled analysis of 3 case-control studies, more than 10 years of marijuana use (joint-years not reported) was associated with TGCT (OR, 1.36; 95% CI, 1.03-1.81; P = .03; I2 = 0%) and nonseminoma TGCT (OR, 1.85; 95% CI, 1.10-3.11; P = .04; I2 = 0%). Evaluations of ever use generally found no association with cancers, but exposure levels were low and poorly defined. Findings for lung cancer were mixed, confounded by few marijuana-only smokers, poor exposure assessment, and inadequate adjustment; meta-analysis was not performed for several outcomes.

Conclusions and Relevance

Low-strength evidence suggests that smoking marijuana is associated with developing TGCT; its association with other cancers and the consequences of higher levels of use are unclear. Long-term studies in marijuana-only smokers would improve understanding of marijuana's association with lung, oral, and other cancers.

Trial Registration

PROSPERO identifier: CRD42018102457.

Long-term nitrite inhalant exposure and cancer risk in MSM

OBJECTIVES

Nitrite inhalants (poppers) are commonly used recreational drugs among MSM and were previously associated with elevated rates of high-risk sexual behavior, HIV and human herpesvirus type 8 (HHV-8) seroconversion, and transient immunosuppressive effects in experimental models. Whether long-term popper use is associated with cancer risk among MSM in the HAART era is unclear.

DESIGN

Prospective cohort study of cancer risk in 3223 HIV-infected and uninfected MSM in the Multicenter AIDS Cohort Study from 1996-2010.

METHODS

Poisson regression models were used to examine the association between heavy popper use (defined as daily or weekly use for at least 1 year) and risk of individual cancers or composite category of virus-associated cancers.

RESULTS

Among all participants, heavy popper use was not associated with increased risk of any individual cancers. Among HIV-uninfected men aged 50-70, heavy popper use was associated with increased risk of virus-associated cancer with causes linked to human papillomavirus, HHV-8, and Epstein-Barr virus in models adjusted for demographics, number of sexual partners, immunological parameters (CD4 cell counts or CD4/CD8 ratios), and hepatitis B and C viruses [incidence rate ratio (IRR), 95% confidence interval (CI) 3.24, 1.05-9.96], or sexually transmitted infections (IRR 3.03, 95% CI, 1.01-9.09), as was cumulative use over a 5-year period (IRR 1.012, 95% CI 1.003-1.021; P = 0.007). There was no significant association between heavy popper use and virus-associated cancer in HIV-infected men.

CONCLUSIONS

Long-term heavy popper use is associated with elevated risk of some virus-associated cancers with causes related to human papillomavirus, HHV-8, and Epstein-Barr virus infections in older HIV-uninfected MSM independent of sexual behavior and immunological parameters.

An epidemiologic review of marijuana and cancer: an update

Marijuana use is legal in two states and additional states are considering legalization. Approximately 18 million Americans are current marijuana users. There is currently no consensus on whether marijuana use is associated with cancer risk. Our objective is to review the epidemiologic studies on this possible association. We identified 34 epidemiologic studies on upper aerodigestive tract cancers (n = 11), lung cancer (n = 6), testicular cancer (n = 3), childhood cancers (n = 6), all cancers (n = 1), anal cancer (n = 1), penile cancer (n = 1), non-Hodgkin lymphoma (n = 2), malignant primary gliomas (n = 1), bladder cancer (n = 1), and Kaposi sarcoma (n = 1). Studies on head and neck cancer reported increased and decreased risks, possibly because there is no association, or because risks differ by human papillomavirus status or geographic differences. The lung cancer studies largely appear not to support an association with marijuana use, possibly because of the smaller amounts of marijuana regularly smoked compared with tobacco. Three testicular cancer case-control studies reported increased risks with marijuana use [summary ORs, 1.56; 95% confidence interval (CI), 1.09-2.23 for higher frequency and 1.50 (95% CI, 1.08-2.09) for ≥10 years]. For other cancer sites, there is still insufficient data to make any conclusions. Considering that marijuana use may change due to legalization, well-designed studies on marijuana use and cancer are warranted.

Influence of noninjecting and injecting drug use on mortality, retention in the cohort, and antiretroviral therapy, in participants in the Swiss HIV Cohort Study

OBJECTIVES

We studied the influence of noninjecting and injecting drug use on mortality, dropout rate, and the course of antiretroviral therapy (ART), in the Swiss HIV Cohort Study (SHCS).

METHODS

Cohort participants, registered prior to April 2007 and with at least one drug use questionnaire completed until May 2013, were categorized according to their self-reported drug use behaviour. The probabilities of death and dropout were separately analysed using multivariable competing risks proportional hazards regression models with mutual correction for the other endpoint. Furthermore, we describe the influence of drug use on the course of ART.

RESULTS

A total of 6529 participants (including 31% women) were followed during 31 215 person-years; 5.1% participants died; 10.5% were lost to follow-up. Among persons with homosexual or heterosexual HIV transmission, noninjecting drug use was associated with higher all-cause mortality [subhazard rate (SHR) 1.73; 95% confidence interval (CI) 1.07-2.83], compared with no drug use. Also, mortality was increased among former injecting drug users (IDUs) who reported noninjecting drug use (SHR 2.34; 95% CI 1.49-3.69). Noninjecting drug use was associated with higher dropout rates. The mean proportion of time with suppressed viral replication was 82.2% in all participants, irrespective of ART status, and 91.2% in those on ART. Drug use lowered adherence, and increased rates of ART change and ART interruptions. Virological failure on ART was more frequent in participants who reported concomitant drug injections while on opiate substitution, and in current IDUs, but not among noninjecting drug users.

CONCLUSIONS

Noninjecting drug use and injecting drug use are modifiable risks for death, and they lower retention in a cohort and complicate ART.

Substance Abuse, Hepatitis C, and Aging in HIV: Common Cofactors that Contribute to Neurobehavioral Disturbances

Although the prevalence of neurocognitive disturbances among individuals with HIV has decreased in recent years, rates of impairment still remain high. This review presents findings from comorbid conditions that may contribute to further neurocognitive impairments in this already vulnerable population. We will focus on three co-factors that have received substantial attention in the neuroAIDS literature: drug use, hepatitis C co-infection (HCV), and aging. All three conditions commonly co-occur with HIV and likely interact with HIV in complex ways. Collectively, the extant literature suggests that drug use, HCV, and aging serve to worsen the neurocognitive profile of HIV through several overlapping mechanisms. A better understanding of how specific comorbidities interact with HIV may reveal specific phenotypes of HIV-associated neurocognitive disorder that may aid in the development of more targeted behavioral and pharmacological treatment efforts.