Smoking Associated with Increased Risk of Recurrence and Mortality among Prostate Cancer Patients after Curative Therapy

SUMMARY: Prostate cancer is the most common cancer in American men with the exclusion of skin cancer, and 1 in 9 men will be diagnosed with prostate cancer during their lifetime. It is estimated that in the United States, about 164,690 new cases of Prostate cancer will be diagnosed in 2018 and 29,430 men will die of the disease. Approximately 35% of the patients with Prostate cancer will experience PSA only relapse within 10 years of their primary treatment with Radical Prostatectomy or Radiation Therapy and a third of these patients will develop documented metastatic disease within 8 years following PSA only relapse. Several studies have addressed how diet and environmental factors affect the risk of Prostate cancer.

According to the American Cancer Society, tobacco use is responsible for nearly 1 in 5 deaths in the United States and accounts for at least 30% of all cancer deaths. Tobacco smoke contains more than 70 well known carcinogens and smoking is known as a preventable risk factor for several genitourinary malignancies cancers such as upper tract urothelial carcinoma, Bladder cancer and Renal Cell Carcinoma. The effect of smoking on the incidence of Prostate cancer has however remained unclear. Nicotine in tobacco smoke has been implicated as a disease driver and there is a significant correlation between smoking and multigene hypermethylation. Further, more unfavorable pathologic features have been noted during Radical Prostatectomy among smokers. Additionally, there is an independent association of cigarette smoking with time to castration resistance, in patients with advanced Prostate cancer undergoing Androgen Deprivation Therapy.

The purpose of this study was to systematically review and analyze the association of smoking status with biochemical recurrence, metastasis, and cancer-specific mortality among patients with localized Prostate cancer undergoing primary curative treatment with radical prostatectomy or radiotherapy. The authors performed a systematic search of original articles published between January 2000 and March 2017 using PubMed, MEDLINE, Embase, and Cochrane Library databases and they identified a total of 5157 studies of which 16 articles were selected for qualitative analysis and 11 articles were selected for quantitative analysis. All included studies were observational and nonrandomized. The meta-analysis overall included 22 549 patients, of whom 4202 (18.6%) were current smokers at the time of primary curative treatment, and 18,347 (81.4%) were nonsmokers (former and never smokers combined). The overall median follow-up was 72 months. The prespecified outcomes evaluated were, biochemical recurrence, metastasis, and cancer-specific mortality.

It was noted that current smokers had a significantly higher risk of experiencing BCR (BioChemical Recurrence) compared with nonsmokers whether they had undergone RP or RT (HR=1.40; P< 0.001). The same findings were noted among former smokers (HR=1.19; P<0.001). Current smokers were also at a higher risk of metastasis (HR=2.51; P<0 .001) and cancer-specific mortality (HR=1.89; P<0.001), but this was not observed among former smokers, for metastasis (HR=1.61; P=0.31) and cancer-specific mortality (HR=1.05; P=0.70).

It was concluded that current smokers at the time of primary curative treatment for localized Prostate cancer are at higher risk of experiencing Biochemical Recurrence, metastasis, and cancer-specific mortality, suggesting that smoking is a modifiable risk factor that affects all disease phases of Prostate cancer. Health Care Providers caring for Prostate cancer patients should be encouraged to counsel patients on smoking cessation, given the risk of poorer outcomes associated with smoking. The authors also noted that this is the first systematic review and meta-analysis that investigated the association of smoking with oncologic outcomes, after primary treatment for localized Prostate cancer. Association of Smoking Status With Recurrence, Metastasis, and Mortality Among Patients With Localized Prostate Cancer Undergoing Prostatectomy or Radiotherapy A Systematic Review and Meta-analysis. Foerster B, Pozo C, Abufaraj M, et al. JAMA Oncol. 2018;4:953-961.