Third Epidemiological Analysis of Nasopharyngeal Carcinoma in the Central Region of Japan from 2006 to 2015

Abstract

The present study aimed to clarify the incidence and clinical outcomes of nasopharyngeal carcinoma (NPC) in the Chubu region of Japan from 2006 to 2015, compared with previous reports. A retrospective analysis was conducted based on medical records from 40 hospitals located in the Chubu region in the central Japanese main island, with a population of around 22.66 million individuals. This study was designed in line with to two previous clinical studies into NPC conducted in the same area of Japan. We recruited NPC patients diagnosed in hospitals across this area over a 10-year period (2006-2015) using a questionnaire about sex, age, primary site, clinical symptoms, pathology, Union for International Cancer Control (UICC) staging, serological exam, treatment, and survival. A total of 620 NPC patients were identified. The age-standardized incidence of NPC from 2006 to 2015 was 0.27 per 100,000 individuals per year. There were no significant differences between this study and the previous two studies conducted in the same area of Japan. The five-year overall survival rate for all patients was 75.9%, while those for patients with stages I, II, III, and IVA were 97%, 91%, 79%, and 68%, respectively. The age-standardized annual incidence of NPC in the present study was 0.27 per 100,000 individuals per year, which was relatively low and stable. The five-year overall survival rate for all NPC patients was significantly improved in this decade compared with previous studies. The smoking rates in male and female NPC patients were 64.5% and 18.8%, respectively, thereby suggesting the involvement of smoking in the incidence of NPC.

Keywords: Japan; incidence; nasopharyngeal carcinoma (NPC); survival.

Figure 1

Number of new cases per age group according to age-specific incidence rates per 100,000 population.

Figure 2

Positive rates of serum antibodies to Epstein–Barr-related antigens. Gray boxes represent anti-EBV-VCA IgG titers of ≥640 mg/dL, and white boxes represent titers of <640 mg/dL. Numbers in the boxes indicate the number of cases. * Fisher test: p < 0.05.

Figure 3

Clinical symptoms. The proportion of each symptom is shown on the horizontal axis. The maximum value on the horizontal axis was adjusted to 60%. Gray boxes indicate patients with symptoms, and the numbers indicate the number of cases.

Figure 4

Pretherapy clinical staging. Patient staging distribution according to the TNM classification of UICC 7th Edition.

Figure 5

Details of curative treatments: (A) The details of curative therapy; (B) the breakdown of the chemotherapy used in 487 cases in which curative chemotherapy and radiotherapy were performed. Platinum includes cisplatin, carboplatin, and nedaplatin. Others alone includes eight cases of S-1 and three cases of DTX. CDDP, cisplatin; DTX, docetaxel; 5FU, 5-fluorouracil; S-1, tegafur/gimeracil/oteracil; TPF, docetaxel/cisplatin/fluorouracil.

Figure 6

Kaplan–Meier curve for overall survival according to stages. Asterisks indicate significant improvement in our study compared with that reported in a previous study (p < 0.05).

Figure 7

Kaplan–Meier curve for overall survival according to pathology. Asterisks indicate significant difference compared with the pathology (p < 0.05).