Cigarette smoking increases the risk of nasopharyngeal carcinoma through the elevated level of IgA antibody against Epstein-Barr virus capsid antigen: A mediation analysis.

BACKGROUND: The study aims are to evaluate the associations between nasopharyngeal carcinoma (NPC) risk and cigarette smoking and to explore the effects of cigarette smoking on Epstein-Barr virus (EBV) infection for NPC risk. METHODS: 1235 male NPC cases and 1262 hospital-based male controls matched to cases were recruited across six collaborative hospitals between 2010 and 2014. Using a standardized questionnaire, information on cigarette smoking and other potential risk factors for NPC was obtained. Blood was collected and used for anti-EBV VCA IgA and anti-EBV EA-EBNA1 IgA testing using standard methods. Unconditional logistic regression analysis was used to estimate odds ratio (OR) with 95% confidence interval (CI) for each risk factor after adjusting for confounders. RESULTS: 63.6% of cases and 44.0% of controls reported ever smoking cigarettes. After full adjustment, current smokers had a significant 1.60-fold (95% CI = 1.30-1.97) and former smokers a borderline significant 1.27-fold (95% CI = 1.00-1.60) increased NPC risk compared to never smokers. NPC risk increased with increasing duration, intensity, and pack-years of cigarette smoking but not with age at smoking initiation. Among controls, anti-EBV VCA IgA seropositivity rate was higher in current smokers than never smokers (14.0% vs 8.4%; OR = 1.82; 95% CI = 1.19-2.79). Mediation analyses showed that more than 90% of the cigarette smoking effect on NPC risk is mediated through anti-EBV VCA IgA. CONCLUSION: This study confirms the association between long-term cigarette smoking and NPC and demonstrates that current smoking is associated with seropositivity of anti-EBV VCA IgA antibodies.

Radiotherapy can decrease locoregional recurrence and increase survival in mastectomy patients with T1 to T2 breast cancer and one to three positive nodes with negative estrogen receptor and positive lymphovascular invasion status.

PURPOSE: To define a subgroup of patients at high risk of locoregional recurrence (LRR) who might be benefit from postmastectomy radiotherapy in invasive breast cancer and tumor size <5 cm with one to three involved axillary lymph nodes (T1-2 N1). METHODS AND MATERIALS: Between April 1991 and December 2005, 544 patients with T1-2 N1 invasive breast cancer were treated with modified radical mastectomy. Of the 544 patients, 383 patients (70.4%) had no radiotherapy, and 161 patients (29.6%) received radiotherapy. We retrospectively compared these two patient groups. RESULTS: With a median follow-up of 40.3 months, LRR occurred in 40 (7.4%) of 544 patients. On univariate analysis, high nuclear grade (p = 0.04), negative estrogen receptor (ER) status (p = 0.001), presence of lymphovascular invasion (LVI) (p = 0.003), and no radiotherapy (p = 0.0015) were associated with a significantly higher rate of LRR. Negative ER status (hazard ratio = 5.1) and presence of LVI (hazard ratio = 2.5) were the risk factors for LRR with statistical significance in the multivariate analysis. Radiotherapy reduced the LRR in patients with the following characteristics: age <40 years, T2 stage, high nuclear grade, negative ER status, and presence of LVI. For 41 patients with negative ER and positive LVI status, radiotherapy can reduce LRR from 10 of 25 (40%) to 2 of 16 (12.5%) and increase the 5-year overall survival from 43.7% to 87.1%. CONCLUSION: Radiotherapy can reduce LRR and increase survival in T1-2 N1 breast cancer patients with negative ER status and presence of LVI.