In endemic regions such as southern China and Southeast Asia, the annual incidence of nasopharyngeal carcinoma (NPC) ranges from 3 to 30 per 100,000. In the Philippines, the estimated incidence in 2010 was 1.2 per 100,000. However, this rate is based on data collected from registries covering only two regions in the country. Here, we report the findings from our study to better approximate the incidence of NPC in the Philippines. Between September 1, 2011 and August 31, 2012, data were collected from 49 patients from 4 different institutions-University of Santo Tomas, Makati Medical Center, Philippine Oncology Center Corporation, and Cardinal Santos Memorial Medical Center-using a NPC screening questionnaire. Crude incidence was 0.09 per 100,000. Age-standardized incidences using Segi and WHO standards were 2.08 and 1.79 per 100,000, respectively. Of the 49 patients, 31 were males and 18 were females, and 71% of patients were between 30 and 59 years old. WHO types II and III represented 22% and 78% of the subjects, respectively, and 75.5% of cases were locally advanced (stages III-IVB). Although the age-standardized incidence from the 4 institutions was numerically higher than the published age-standardized incidence (2.07 per 100,000 vs. 1.2 per 100,000), two-proportion z-test showed no significant difference between them (P = 0.68). A more concerted effort is needed for a better approximation of the country's NPC disease burden.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Carcinoma ; Child ; Female ; Humans ; Incidence ; Male ; Middle Aged ; Nasopharyngeal Neoplasms ; epidemiology ; pathology ; Neoplasm Staging ; Philippines ; epidemiology ; Registries ; Surveys and Questionnaires ; Young Adult

Objectives: The authors' aim was to conduct a dosimetric analysis of the incidental radiation dose to the internal mammary node (IMN) region using a three-field chest wall technique (TFCWT).

Methods: This retrospective study utilized 3D-conformal radiotherapy plans of 50 postmastectomy patients (25 left-sided and 25 rightsided). All plans used the TFCWT, composed of narrowed tangents matched medially to an AP electron field, and prescribed a total dose of 50 Gy in 28 fractions. The IMNs were not intentionally treated in all included plans.

Results: The mean dose to the IMN-planning target volume (IMN-PTV) was 45.1 Gy (26.4 - 55.6, SD 6.5). Minimum doses received by 95% and 90% of the IMN-PTV were 29.3 Gy (8 - 49, SD 10.0) and 34.0 Gy (10.0 - 52.0, SD 8.6), respectively. The percent volume of IMN-PTV receiving 100%, 95%, 90%, and 80% were 47.4% (3 - 94, SD 21.6), 55.6% (6 - 97, SD 22.4), 61.92% (7 - 98, SD 22.2), and 72.61% (18-100, SD 20.2), respectively. The average ipsilateral lung V20 Gy (with supraclavicular fields) was 25.0% (16 - 29, SD 3.4), and the average heart mean dose was 2.5 Gy (0.5 - 7.9, SD 1.58).

Conclusion: Although the results suggest increased IMN radiation doses with the TFCWT when compared historically to standard tangents, the incidental doses are comparatively less than that traditionally prescribed to the IMNs in high-risk patients. It is unknown whether this incidental IMN dose confers any clinical benefit.