Mendelian randomisation analysis provides no evidence for a relationship between adult height and testicular cancer risk

Obesity and main urologic cancers: Current systematic evidence, novel biological mechanisms, perspectives and challenges

Urologic cancers (UC) account for 13.1% of all new cancer cases and 7.9% of all cancer-related deaths. A growing body of evidence has indicated a potential causal link between obesity and UC. The aim of the present review is to appraise in a critical and integrative manner evidence from meta-analyses and mechanistic studies on the role of obesity in four prevalent UC (kidney-KC, prostate-PC, urinary bladder-UBC, and testicular cancer-TC). Special emphasis is given on Mendelian Randomization Studies (MRS) corroborating a genetic causal association between obesity and UC, as well as on the role of classical and novel adipocytokines. Furthermore, the molecular pathways that link obesity to the development and progression of these cancers are reviewed. Available evidence indicates that obesity confers increased risk for KC, UBC, and advanced PC (20-82%, 10-19%, and 6-14%, respectively), whereas for TC adult height (5-cm increase) may increase the risk by 13%. Obese females tend to be more susceptible to UBC and KC than obese males. MRS have shown that a higher genetic-predicted BMI may be causally linked to KC and UBC but not PC and TC. Biological mechanisms that are involved in the association between excess body weight and UC include the Insulin-like Growth Factor axis, altered availability of sex hormones, chronic inflammation and oxidative stress, abnormal secretion of adipocytokines, ectopic fat deposition, dysbiosis of the gastrointestinal and urinary tract microbiomes and circadian rhythm dysregulation. Anti-hyperglycemic and non-steroidal anti-inflammatory drugs, statins, and adipokine receptor agonists/antagonists show potential as adjuvant cancer therapies. Identifying obesity as a modifiable risk factor for UC may have significant public health implications, allowing clinicians to tailor individualized prevention strategies for patients with excess body weight.

Systematic review of Mendelian randomization studies on risk of cancer

BACKGROUND

We aimed to map and describe the current state of Mendelian randomization (MR) literature on cancer risk and to identify associations supported by robust evidence.

METHODS

We searched PubMed and Scopus up to 06/10/2020 for MR studies investigating the association of any genetically predicted risk factor with cancer risk. We categorized the reported associations based on a priori designed levels of evidence supporting a causal association into four categories, namely robust, probable, suggestive, and insufficient, based on the significance and concordance of the main MR analysis results and at least one of the MR-Egger, weighed median, MRPRESSO, and multivariable MR analyses. Associations not presenting any of the aforementioned sensitivity analyses were not graded.

RESULTS

We included 190 publications reporting on 4667 MR analyses. Most analyses (3200; 68.6%) were not accompanied by any of the assessed sensitivity analyses. Of the 1467 evaluable analyses, 87 (5.9%) were supported by robust, 275 (18.7%) by probable, and 89 (6.1%) by suggestive evidence. The most prominent robust associations were observed for anthropometric indices with risk of breast, kidney, and endometrial cancers; circulating telomere length with risk of kidney, lung, osteosarcoma, skin, thyroid, and hematological cancers; sex steroid hormones and risk of breast and endometrial cancer; and lipids with risk of breast, endometrial, and ovarian cancer.

CONCLUSIONS

Despite the large amount of research on genetically predicted risk factors for cancer risk, limited associations are supported by robust evidence for causality. Most associations did not present a MR sensitivity analysis and were thus non-evaluable. Future research should focus on more thorough assessment of sensitivity MR analyses and on more transparent reporting.

Denial and oncological pathology: Case report of a massive testicular cancer

LITERATURE

The cancer of testicles represents 1% of male neoplasms and 5% of urological malignant neoplasm. Its incidence has been growing in Western societies. Cancer of testicles usually presents as an increase of consistence in one testicles and absence of pain, as a casual ultrasound scan finding, or it could be highlighted by a scrotal injury. The surgical treatment is either radical orchiectomy or radical orchiectomy plus retroperitoneal lymph node dissection.

CASE PRESENTATION

The case presented concerns a 48-year-old male with a history of left testicular trauma and subsequent hypotrophy. Over the next 4 years, the patient developed a testicle size increase up to 15 cm in diameter. At diagnosis, he had retroperitoneal lymphadenopathy. The patient was, after surgery, referred to the oncology department.

CONCLUSION

The awareness of the male population respect to testicular cancer and its screening methods (e.g. self-examination) is essential to make the diagnosis at an early stage. It is also essential to psychologically support patients undergoing surgical and/or pharmacological therapy due to risk of determining anxiety or depression compared to the whole population.

The puzzling incidence of testicular cancer in New Zealand: what can we learn?

BACKGROUND

Testicular germ cell tumour is the most common cancer to be diagnosed among young men. In New Zealand, we have observed some puzzling trends in the epidemiology of this disease.

METHODS

We have conducted a narrative review of available evidence regarding the puzzling epidemiology of testicular germ cell tumour in New Zealand and discussed the possible drivers of these trends.

RESULTS AND DISCUSSION

Whereas testicular cancer is most commonly a disease of White men, in New Zealand it is the indigenous Māori population that suffer by far the greatest rate of disease (age-adjusted relative risk: 1.80, 95% CI 1.58-2.05). Even more curiously, the rate of testicular germ cell tumour among Māori men aged 15-44 (28/100,000) is substantially greater than for Pacific Island men (9/100,000), a rare example of divergence between these two populations in terms of the incidence of any disease (cancer or otherwise). Our observations beg the following questions: first, why are rates of testicular germ cell tumour so much higher among Māori New Zealanders compared to the already high rates observed among European/Other New Zealanders? Second, why are rates of testicular germ cell tumour so completely divergent between Māori and Pacific New Zealanders, when these two groups typically move in parallel with respect to the incidence of given diseases? Finally, what might we learn about the factors that cause testicular germ cell tumour in general by answering these questions?

CONCLUSION

This review examines the possible drivers of our observed disparity, discusses their feasibility, and highlights new work that is underway to further understand these drivers.