Cannabis smoke can be a major risk factor for early-age laryngeal cancer—a molecular signaling-based approach

Role of Cannabinoids in Oral Cancer

Cannabinoids have incited scientific interest in different conditions, including malignancy, due to increased exposure to cannabis. Furthermore, cannabinoids are increasingly used to alleviate cancer-related symptoms. This review paper aims to clarify the recent findings on the relationship between cannabinoids and oral cancer, focusing on the molecular mechanisms that could link cannabinoids with oral cancer pathogenesis. In addition, we provide an overview of the current and future perspectives on the management of oral cancer patients using cannabinoid compounds. Epidemiological data on cannabis use and oral cancer development are conflicting. However, in vitro studies assessing the effects of cannabinoids on oral cancer cells have unveiled promising anti-cancer features, including apoptosis and inhibition of cell proliferation. Downregulation of various signaling pathways with anti-cancer effects has been identified in experimental models of oral cancer cells exposed to cannabinoids. Furthermore, in some countries, several synthetic or phytocannabinoids have been approved as medical adjuvants for the management of cancer patients undergoing chemoradiotherapy. Cannabinoids may improve overall well-being by relieving anxiety, depression, pain, and nausea. In conclusion, the link between cannabinoid compounds and oral cancer is complex, and further research is necessary to elucidate the potential risks or their protective impact on oral cancer.

Causal relationship between cannabis use and cancer: a genetically informed perspective

PURPOSE

Cannabis use is increasing legally worldwide, while its impact on cancer risk is unclear. This study was performed to investigate the relationship between cannabis use and the risk of several types of cancer.

METHODS

We conducted a two-sample Mendelian randomization (MR) study to explore the causality of cannabis use on 9 site-specific types of cancer including breast cancer, cervical cancer, melanoma, colorectal cancer, laryngeal cancer, oral cancer, oropharyngeal cancer, esophageal cancer, and glioma. Genome-wide significant genetic instruments (P < 5E-06) for cannabis use were extracted from a large-scale genome-wide association meta-analysis of European ancestry, whereas cancer genetic instruments were extracted from the UK Biobank (UKB) cohort and GliomaScan consortium in the OpenGWAS database. The inverse-variance weighted (IVW) was considered the main method for MR analysis, and sensitivity analyses including MR-Egger, weighted median, MR pleiotropy residual sum, and outlier test (MR-PRESSO) were conducted to evaluate the robustness of the results.

RESULTS

Cannabis use was a significant promoting factor for cervical cancer (OR = 1.001265, 95% CI 1.000375-1.002155, P = 0.0053). And we also detected suggestive evidence of the causality of cannabis use on laryngeal cancer (OR = 1.000350, 95% CI 1.000027-1.000672, P = 0.0336) and breast cancer (OR = 1.003741, 95% CI 1.000052-1.007442, P = 0.0467). No evidence of a causal association of cannabis use with other site-specific types of cancer was detected. Additionally, no pleiotropy or heterogeneity was found in the sensitivity analysis.

CONCLUSION

This study indicates a causative association of cannabis use on cervical cancer, while cannabis use may increase the odds of breast cancer and laryngeal cancer, which require further evaluation in large-scale population-based studies.

An Individuality of Response to Cannabinoids: Challenges in Safety and Efficacy of Cannabis Products

Since legalization, cannabis/marijuana has been gaining considerable attention as a functional ingredient in food. ∆-9 tetrahydrocannabinol (THC), cannabidiol (CBD), and other cannabinoids are key bioactive compounds with health benefits. The oral consumption of cannabis transports much less hazardous chemicals than smoking. Nevertheless, the response to cannabis is biphasically dose-dependent (hormesis; a low-dose stimulation and a high-dose inhibition) with wide individuality in responses. Thus, the exact same dose and preparation of cannabis may be beneficial for some but toxic to others. The purpose of this review is to highlight the concept of individual variations in response to cannabinoids, which leads to the challenge of establishing standard safe doses of cannabis products for the general population. The mechanisms of actions, acute and chronic toxicities, and factors affecting responses to cannabis products are updated. Based on the literature review, we found that the response to cannabis products depends on exposure factors (delivery route, duration, frequency, and interactions with food and drugs), individual factors (age, sex), and susceptibility factors (genetic polymorphisms of cannabinoid receptor gene, N-acylethanolamine-hydrolyzing enzymes, THC-metabolizing enzymes, and epigenetic regulations). Owing to the individuality of responses, the safest way to use cannabis-containing food products is to start low, go slow, and stay low.

Diagnostic and Prognostic Value of microRNAs in Patients with Laryngeal Cancer: A Systematic Review

Laryngeal squamous cell cancer (LSCC) is one of the most common malignant tumors of the head and neck region, with a poor survival rate (5-year overall survival 50-80%) as a consequence of an advanced-stage diagnosis and high recurrence rate. Tobacco smoking and alcohol abuse are the main risk factors of LSCC development. An early diagnosis of LSCC, a prompt detection of recurrence and a more precise monitoring of the efficacy of different treatment modalities are currently needed to reduce the mortality. Therefore, the identification of effective diagnostic and prognostic biomarkers for LSCC is crucial to guide disease management and improve clinical outcomes. In the past years, a dysregulated expression of small non-coding RNAs, including microRNAs (miRNAs), has been reported in many human cancers, including LSCC, and many miRNAs have been explored for their diagnostic and prognostic potential and proposed as biomarkers. We searched electronic databases for original papers that were focused on miRNAs and LSCC, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. According to the outcome, 566 articles were initially screened, of which 177 studies were selected and included in the analysis. In this systematic review, we provide an overview of the current literature on the function and the potential diagnostic and prognostic role of tissue and circulating miRNAs in LSCC.

Geospatiotemporal and causal inference study of cannabis and other drugs as risk factors for female breast cancer USA 2003-2017

Breast cancer (BC) is the commonest human cancer and its incidence (BC incidence, BCI) is rising worldwide. Whilst both tobacco and alcohol have been linked to BCI genotoxic cannabinoids have not been investigated. Age-adjusted state-based BCI 2003-2017 was taken from the Surveillance Epidemiology and End Results database of the Centers for Disease Control. Drug use from the National Survey of Drug Use and Health, response rate 74.1%. Median age, median household income and ethnicity were from US census. Inverse probability weighted (ipw) multivariable regression conducted in R. In bivariate analysis BCI was shown to be significantly linked with rising cannabis exposure {β-est. = 3.93 [95% confidence interval 2.99, 4.87], P = 1.10 × 10^-15}. At 8 years lag cigarettes:cannabis [β-est. = 2660 (2150.4, 3169.3), P = 4.60 × 10^-22] and cannabis:alcoholism [β-est. = 7010 (5461.6, 8558.4), P = 1.80 × 10^-17] were significant in ipw-panel regression. Terms including cannabidiol [CBD; β-est. = 16.16 (0.39, 31.93), P = 0.446] and cannabigerol [CBG; β-est. = 6.23 (2.06, 10.39), P = 0.0034] were significant in spatiotemporal models lagged 1:2 years, respectively. Cannabis-liberal paradigms had higher BCI [67.50 ± 0.26 v. 65.19 ± 0.21/100 000 (mean ± SEM), P = 1.87 × 10^-11; β-est. = 2.31 (1.65, 2.96), P = 9.09 × 10^-12]. 55/58 expected values >1.25 and 13/58 >100. Abortion was independently and causally significant in space-time models. Data show that exposure to cannabis and the cannabinoids Δ9-tetrahydrocannabinol, CBD, CBG and alcoholism fulfil quantitative causal criteria for BCI across space and time. Findings are robust to adjustment for age and several known sociodemographic, socio-economic and hormonal risk factors and establish cannabinoids as an additional risk factor class for breast carcinogenesis. BCI is higher under cannabis-liberal legal paradigms.

Cannabis related side effects in otolaryngology: a scoping review

BACKGROUND

Cannabis has been rapidly legalized in North America; however, limited evidence exists around its side effects. Health Canada defines side effect as a harmful and unintended response to a health product. Given drug safety concerns, this study's purpose was to review the unintended side effects of cannabis in otolaryngology.

METHODS

The Preferred Reporting Items For Systematic Reviews and Meta-analysis extension for Scoping Reviews (PRISMA-ScR) protocol was used to conduct a scoping review of the MEDLINE, EMBASE, CINAHL, and CENTRAL databases. (PROSPERO: CRD42020153022). English studies in adults were included from inception to the end of 2019. In-vitro, animal, and studies with n < 5 were excluded. Primary outcome was defined as unintended side effects (defined as any Otolaryngology symptom or diagnosis) following cannabis use. Oxford Centre for Evidence-Based Medicine: Levels of Evidence and risk of bias using the Risk of Bias in randomized trials (RoB 2) and Risk of Bias in Non-Randomized Studies of Interventions (ROBINS-I) tools were assessed.. Two authors independently reviewed all studies; the senior author settled any discrepancies.

RESULTS

Five hundred and twenty-one studies were screened; 48 studies were analysed. Subspecialties comprised: Head and Neck (32), Otology (8), Rhinology (5), Airway (5), Laryngology (1). Cannabis use was associated with unintended tinnitus, vertigo, hearing loss, infection, malignancy, sinusitis, allergic rhinitis, thyroid dysfunction, and dyspnea. About half (54.1%) of studies showed increased side effects, or no change in symptoms following cannabis use. Oxford Levels of Evidence was 2-4 with substantial heterogeneity. Risk of bias assessment with RoB2 was low to high and ROBINS-1 was moderate to critical.

CONCLUSION

This was the first comprehensive scoping review of unintended side effects of cannabis in Otolaryngology. The current literature is limited and lacks high-quality research Future randomized studies are needed to focus on therapeutic effects of cannabis in otolaryngology. Substantial work remains to guide clinicians to suggest safe, evidence-based choices for cannabis use.

Exposure to chewing tobacco promotes primary oral squamous cell carcinoma and regional lymph node metastasis by alterations of SDF1α/CXCR4 axis

A high incidence of oral squamous cell carcinoma (OSCC) is observed in South-East Asian countries due to addictions such as chewing tobacco. Local invasion and distant metastases are primary causes of poor prognosis in OSCC. This study aimed to understand the alterations in metastasis biomarkers, such as stromal cell-derived factor-1α (SDF-1 or SDF1α) and its receptor C-X-C chemokine receptor type 4 (CXCR4), in OSCC patient samples that were stratified based on the history of addiction to chewing tobacco. Targeted immunohistochemical staining and Western blotting were performed on primary tumour and metastatic lymph node (LN) tissues in parallel. Overexpression of hepatocyte growth factor (HGF), activated form of its cognate receptor tyrosine kinase, c-Met (p-Met), GRB2-associated-binding protein 1 (Gab1), phospho-protein kinase B (pAkt), nuclear factor kappa B (NF-κB) and cyclooxygenase-2 (COX-2) were observed in primary tumour and metastatic lymph nodes in both chewer and non-chewer cohorts. Variance analysis showed significant positive correlation between them (P < .0001) indicating upregulation of these biomarkers upon ligand-induced activation of c-Met in both tobacco chewers and non-chewers. Significantly higher expressions of SDF1α and CXCR4 were observed in both primary tumours and metastatic lymph nodes of tobacco chewers (P < .0001) and coincided with overexpressed HGF. In contrast, no significant correlation was observed between expression of HGF and that of SDF1α and CXCR4 in non-chewers. Together, our findings provide important insights into the association of HGF/c-Met and the SDF1α/CXCR4 axis in lymph node metastasis and to an aetiological link with the habit of chewing tobacco.

Patterns of urgent hoarseness referrals to ENT-When should we be suspicious of cancer?

BACKGROUND

Current UK referral criteria stipulate that hoarseness should be persistent to merit 2 week wait (2WW) or urgent suspicion of cancer (USOC) referral. This study delineates patterns of hoarseness presentation with a view to assisting referral pathways, and whereby reassurance could be provided.

METHODS

A pre-existing database of patients referred with hoarseness under the urgent suspicion of cancer (USOC) category was analysed. Univariate and multivariate analyses were performed on a variety of demographic and comorbid features to produce odds ratios (OR) of features either related or not related to laryngeal cancer.

RESULTS

Of 698 consecutive hoarseness referrals were studied. In these referrals there were 506(73%) with persistent hoarseness and 192(27%) with intermittent hoarseness. The most significant patient variables related to laryngeal cancer were persistent hoarseness (OR 4.97), recreational drug use (OR 4.94), male gender (OR 4.01) and weight loss (OR 3.75). Significant patient variables present not related to laryngeal cancer diagnosis were intermittent hoarseness (OR 0.2), the presence of cough (OR 0.2), globus sensation (OR 0.25) and recent viral infection (OR 0.29).

CONCLUSION

The strongest association with cancer is seen in patients that are persistently hoarse. Patients with fluctuating hoarseness do not need an "urgent suspicion of cancer" referral. Additional demographic referral information could help to streamline the referral of these patients, and reassure others.

Therapeutic Application of Cannabis in Medicine and Its Relevance to Thoracic Surgery

BACKGROUND

Cannabis is the most commonly used illicit substance in the United States. As cannabis use rises in popularity and its legalization continues to expand, the scientific community must address the controversy between beneficial and adverse effects of cannabis consumption.

METHODS

We performed a comprehensive literature review to study the medicinal and pathologic effects of cannabis use, with emphasis on its association with cancer pathophysiology and thoracic surgery.

RESULTS

We found evidence that cannabis products often contain carcinogenic materials and that their use is associated with the development of certain head and neck cancers, but not lung cancer. Indeed, several in vitro and in vivo studies have demonstrated that cannabis may have a therapeutic role in cancer given the antiproliferative effects of its active compounds such as δ-9-tetrahydrocannabinol. Cannabis-derived products have also been shown to be effective treatments for chronic pain, neuropathy, spasticity, and as antiemetics.

CONCLUSIONS

We acknowledge that additional studies are required to elucidate the long-term effects of cannabis products and that many potential biases and limitations exist in the literature due to self-reporting and limited survey studies. Appropriate stewardship over cannabis use among our patient population will likely determine its full implications in both oncologic and perioperative outcomes.

What is the evidence for cannabis use in otolaryngology?: A narrative review

OBJECTIVES

Review of the English literature for all studies involving cannabis and Otolaryngology.

METHODS

PubMed was searched using a combination of the terms cannabis, marijuana, otolaryngology, hearing, tinnitus, vestibular, rhinology, sinusitis, laryngology, voice, airway, head and neck, head and neck cancer, facial trauma, spasm, pediatric otolaryngology, sleep medicine, obstructive sleep apnea, and other variations. Literature included in the review provided substantive research on cannabis in Otolaryngology.

RESULTS

Seventy-nine unique publications were found in the literature. The majority were published in the last decade and pertain to the subspecialty of Head and Neck; specifically, its association with incident cancers. A small number of studies exist that suggest cannabis may be a useful therapy for Otolaryngological patients suffering from blepharospasm, the effects of radiation, and the psychological sequelae of receiving a cancer diagnosis.

CONCLUSION

Further research is required to determine the potential therapeutic roles and adverse effects of cannabis on conditions related to Otolaryngology. This study serves the Otolaryngological researcher with the most current, comprehensive literature review for the exploration into possible projects to undertake.

Pulmonary effects of inhaled cannabis smoke

Background: The smoke generated from cannabis delivers biologically active cannabinoids and a number of combustion-derived toxins, both of which raise questions regarding the impact of cannabis smoking on lung function, airway inflammation and smoking-related lung disease.Objectives: Review the potential effects of cannabis smoking on respiratory symptoms, lung function, histologic/molecular alterations in the bronchial mucosa, smoking-related changes in alveolar macrophage function and the potential clinical impact of cannabis smoking on chronic obstructive pulmonary disease, lung cancer and pulmonary infections.Methods: Focused literature review.Results: The carcinogens and respiratory toxins in cannabis and tobacco smoke are similar but the smoking topography for cannabis results in higher per-puff exposures to inhaled tar and gases. The frequency of chronic cough, sputum and wheeze and the presence of airway mucosal inflammation, goblet cell and vascular hyperplasia, metaplasia and cellular disorganization are similar between cannabis smokers and tobacco smokers. Cannabis smoke has modest airway bronchodilator properties but of unclear clinical significance. While clear evidence exists for progression to obstructive lung disease and emphysema in chronic tobacco smokers, the effects from habitual cannabis use are less clear. Evidence suggests that alveolar macrophages from cannabis smokers have deficits in cytokine production and antimicrobial activity not present in cells from tobacco smokers.Conclusions: Solid conclusions regarding the respiratory consequences of regular cannabis smoking are difficult to make due to a relative paucity of literature, confounding by concurrent tobacco smoking and reports of conflicting outcomes. Additional well-controlled clinical studies on the pulmonary consequences of habitual cannabis use are needed.

Marijuana and Lung Disease

As marijuana smoking prevalence increases in the United States, concern regarding its potential risks to lung health has also risen, given the general similarity in the smoke contents between marijuana and tobacco. Most studies have found a significant association between marijuana smoking and chronic bronchitis symptoms after adjustment for tobacco. Although reports are mixed regarding associations between marijuana smoking and lung function, none have shown a relationship to decrements in FEV₁ and few have found a relationship to a decreased ratio of FEV₁/FVC, possibly related to an association between marijuana and an increased FVC. A few studies have found a modest reduction in specific airway conductance in relation to marijuana, probably reflecting endoscopic evidence of bronchial mucosal edema among habitual marijuana smokers. Diffusing capacity in marijuana smokers has been normal, and two studies of thoracic high-resolution CT scan have not shown any association of marijuana smoking with emphysema. Although bronchial biopsies from habitual marijuana smokers have shown precancerous histopathologic changes, a large cohort study and a pooled analysis of six well-designed case-control studies have not found evidence of a link between marijuana smoking and lung cancer. The immunosuppressive effects of delta-9 tetrahydrocannabinol raise the possibility of an increased risk of pneumonia, but further studies are needed to evaluate this potential risk. Several cases series have demonstrated pneumothoraces/pneumomediastinum and bullous lung disease in marijuana smokers, but these associations require epidemiologic studies for firmer evidence of possible causality.

Vocal assessment of addicts on methadone therapy via the RBH scale and objective acoustic parameters

INTRODUCTION

A large number of people around the world struggle daily to become free of their addiction to illegal psychoactive substances. In order to create an atmosphere of improved supervision, established communication and improved quality of life for drug addicts, centers have been set up to provide methadone as a substitute.

OBJECTIVE

The aim of the research was to assess the vocal features of drug addicts on methadone therapy via subjective and objective parameters, to ascertain if vocal damage has occurred and to determine whether subjective and objective acoustic vocal parameters are related, and how.

METHODS

The research included 34 adults of both genders who were undergoing methadone treatment. A subjective vocal evaluation assessed voice pitch and clarity, while the subjective acoustic analysis utilized the Roughness-Breathiness-Hoarseness scale of roughness-breathiness-hoarseness. Objective acoustic analysis was conducted after recording and analyzing an uninterrupted vocal /a/ of at least three seconds duration, using the "GllotisController" software.

RESULTS

The subjective acoustic analysis using the Roughness-Breathiness-Hoarseness scale showed pathological values in 52.9% male and 47% female participants. The average values of the roughness-breathiness-hoarseness for the entire sample were 0.91, 0.38 and 0.50, respectively. Lower roughness was associated with a higher fundamental frequency (f₀) and lower jitter and shimmer values (p<0.05). There was a statistically significant correlation between breathiness, jitter (p<0.01) and shimmer (p<0.05), and between hoarseness and jitter (p<0.01).

CONCLUSION

A statistically significant correlation was found between the two subjective vocal assessments, voice clarity and pitch, and Roughness-Breathiness-Hoarseness scale, and the parameters of the objective acoustic vocal assessment.

The Prognostic Value of Epithelial Membrane Protein 1 (EMP-1) in Patients with Laryngeal Carcinoma

Background

In the present study, we aimed to investigate the prognostic value of epithelial membrane protein 1 (EMP-1) gene in patients diagnosed with laryngeal carcinoma (LC).

Material/Methods

Patients who were pathologically diagnosed with LC were enrolled in the present study. The expression levels of EMP-1 in tumor tissues and corresponding normal tissues collected from the LC patients were detected by semi-reverse transcriptase polymerase chain reaction (semi-RT-PCR). Chi-square analysis was used to evaluate the relationship between EMP-1 expression level and clinical characteristics. Survival analysis for the study population was analyzed by Kaplan-Meier method with log rank test. Additionally, Cox regression model was applied to evaluate the prognostic value of EMP-1 in LC patients.

Results

106 LC patients, including 55 men and 51 women, were enrolled in the present study. Semi-RT-PCR demonstrated that the expression level of EMP-1 was decreased in tumor tissues, compared with adjacent normal tissues (p<0.001). Moreover, the level was significantly associated with lymph node metastasis, histological grade, and clinical stage (p<0.05 for all). In addition, low levels of EMP-1 was significantly correlated with poor survival rate (log rank test, p=0.020). Cox regression analysis indicated that EMP-1 was an independent marker for LC prognosis (HR=2.755, 95% CI=1.123–6.760, p=0.027).

Conclusions

The abnormal expression of EMP-1 may be associated with progression of LC and the gene may act as a prognostic marker for LC.

CDKN2A-p53 mediated antitumor effect of Lupeol in head and neck cancer

PURPOSE

The tumor suppressor protein p53 is known to control cell cycle arrest and apoptosis. Lupeol is a phytochemical that has been found to induce apoptosis in different cancer types through the extrinsic pathway. As yet, however, its role in the induction of cell cycle arrest and apoptosis through the intrinsic pathway in head and neck cancer has not been investigated. Here, we aimed at understanding the mechanism underlying the antitumor effect of Lupeol in head and neck cancer.

METHODS

The antitumor effect of Lupeol on oral and laryngeal carcinomas was assessed using two in vitro 2D cell line models (HEp-2, UPCI:SCC-131) and, subsequently, an ex vivo 3D tumor explant culture platform that maintains key features of the native tumor microenvironment. The mechanism underlying Lupeol-mediated antitumor responses was delineated using MTT, colony formation, flow cytometry, immunofluorescence, Western blotting and immunohistochemistry assays.

RESULTS

We found that Lupeol induced an enhanced expression of p53 in both cell line models tested and, subsequently, cell cycle arrest at the G1 phase. In addition we found that, following Lupeol treatment, p53 induced Bax expression and activated the intrinsic apoptotic pathway (as measured by Caspase-3 cleavage). Interestingly, Lupeol was also found to trigger G1 cell cycle arrest through up-regulation of the expression of CDKN2A, but not p21, resulting in inhibition of CyclinD1. In an ex vivo platform Lupeol was found to impart a potent antitumor response as defined by inhibition of Ki67 expression, decreased cell viability and concomitant activation (cleavage) of Caspase-3. Finally, we found that Lupeol can re-sensitize primary head and neck squamous cell carcinoma (HNSCC) tumor samples that had clinically progressed under a Cisplatin treatment regimen.

CONCLUSION

Together, our data indicate that Lupeol may orchestrate a bifurcated regulation of neoplastic growth and apoptosis in head and neck cancers and may serve as a promising agent for the management of tumors that have progressed on a platinum-based treatment regimen.

Primary Lingual Colonic-Type Adenocarcinoma: A Rare and Emerging Distinct Entity!

Primary colonic-type adenocarcinoma involving the tongue (CTAT) is exquisitely rare, with only four cases having been reported in the literature. We report the case of a 53-year-old woman with an anterior (oral) tongue mass. A review of literature was performed. Histomorphologic features were evaluated with standard hematoxylin and eosin stained sections. Ancillary testing was performed. The mass consisted of invasive adenocarcinoma associated with "dirty necrosis", akin to the phenotype seen in colorectal adenocarcinoma. By immunohistochemistry, the tumor cells were positive for AE1/3, CDX2, CK20, SATB2 and beta-catenin. This was initially felt to represent a metastatic colorectal adenocarcinoma but subsequent PET/CT and colonoscopy examination were negative for colorectal mass, excluding the possibility of a metastasis and confirming a diagnosis of CTAT. We raise awareness of the existence of this entity and recommend that metastatic disease be excluded before rendering a diagnosis of CTAT.

Chromothripsis and epigenomics complete causality criteria for cannabis- and addiction-connected carcinogenicity, congenital toxicity and heritable genotoxicity

The recent demonstration that massive scale chromosomal shattering or pulverization can occur abruptly due to errors induced by interference with the microtubule machinery of the mitotic spindle followed by haphazard chromosomal annealing, together with sophisticated insights from epigenetics, provide profound mechanistic insights into some of the most perplexing classical observations of addiction medicine, including cancerogenesis, the younger and aggressive onset of addiction-related carcinogenesis, the heritability of addictive neurocircuitry and cancers, and foetal malformations. Tetrahydrocannabinol (THC) and other addictive agents have been shown to inhibit tubulin polymerization which perturbs the formation and function of the microtubules of the mitotic spindle. This disruption of the mitotic machinery perturbs proper chromosomal segregation during anaphase and causes micronucleus formation which is the primary locus and cause of the chromosomal pulverization of chromothripsis and downstream genotoxic events including oncogene induction and tumour suppressor silencing. Moreover the complementation of multiple positive cannabis-cancer epidemiological studies, and replicated dose-response relationships with established mechanisms fulfils causal criteria. This information is also consistent with data showing acceleration of the aging process by drugs of addiction including alcohol, tobacco, cannabis, stimulants and opioids. THC shows a non-linear sigmoidal dose-response relationship in multiple pertinent in vitro and preclinical genotoxicity assays, and in this respect is similar to the serious major human mutagen thalidomide. Rising community exposure, tissue storage of cannabinoids, and increasingly potent phytocannabinoid sources, suggests that the threshold mutagenic dose for cancerogenesis will increasingly be crossed beyond the developing world, and raise transgenerational transmission of teratogenicity as an increasing concern.