Epidemiology and Clinicopathology of Breast Cancer in Metro Manila and Rizal Province, Philippine


The breast cancer incidence in the Philippines is among the highest in Asia. Age-standardized incidencerates (ASR) in Metro Manila and Rizal Province derived from the Philippine Cancer Society-Manila CancerRegistry and the Department of Health-Rizal Cancer Registry showed increase from 1980 to 2002, and weresignificantly higher in 7 cities in Metro Manila and significantly lower in 14 cities/municipalities mostly in RizalProvince. The AJCC Clinical Stage did not change from 1993 to 2002 among incident cases, the averagedistribution being: I=5%, IIA=20%, IIB= 18%, IIIA=9%, IIIB=10%, IV=11%, Unknown=28%. TheInternational Agency for Research on Cancer attempted to run a randomized screening trial in 1995-1997 in thePhilippines based on clinical breast examination by trained nurses and midwives. Unfortunately, even afterhome visits by a team equipped to perform needle biopsy, only 35% of screen-positive cases eventually had adiagnostic test. The estimated prevalence of BRCA mutations among unselected patients in the Philippine GeneralHospital (PGH) in 1998 was 5.1%, with a prevalence of 4.1% for BRCA2 mutations alone. There is a continuingeffort at improving IHC hormone receptor testing at PGH, particularly on early fixation in buffered formalin.It was observed that hormone receptor-positive proportions tended to be higher in core needle biopsy specimens(72%) compared to mastectomy specimens (65%). During the years 1991, 1994 and 1997, 97% of incident casesof early breast cancer underwent modified radical mastectomy, 18% had postoperative radiotherapy, 51% hadadjuvant hormone treatment and 47% received adjuvant chemotherapy. Survival of incident cases in 1993 to2002 was compared to that of Filipino-Americans and Caucasians in the SEER 13 database. The age-adjusted 5-year relative survival, using period analysis, of Metro Manila residents, Filipino-Americans and Caucasianswere 58.6%, 89.6% and 88.3% respectively.