Epidemiology and clinicopathology of breast cancer in metro Manila and Rizal Province, Philippines.

Abstract

The breast cancer incidence in the Philippines is among the highest in Asia. Age-standardized incidence rates (ASR) in Metro Manila and Rizal Province derived from the Philippine Cancer Society-Manila Cancer Registry and the Department of Health-Rizal Cancer Registry showed increase from 1980 to 2002, and were significantly higher in 7 cities in Metro Manila and significantly lower in 14 cities/municipalities mostly in Rizal Province. The AJCC Clinical Stage did not change from 1993 to 2002 among incident cases, the average distribution being: I= 5%, IIA= 20%, IIB= 18%, IIIA= 9%, IIIB= 10%, IV= 11%, Unknown= 28%. The International Agency for Research on Cancer attempted to run a randomized screening trial in 1995-1997 in the Philippines based on clinical breast examination by trained nurses and midwives. Unfortunately, even after home visits by a team equipped to perform needle biopsy, only 35% of screen-positive cases eventually had a diagnostic test. The estimated prevalence of BRCA mutations among unselected patients in the Philippine General Hospital (PGH) in 1998 was 5.1%, with a prevalence of 4.1% for BRCA2 mutations alone. There is a continuing effort 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 cases of early breast cancer underwent modified radical mastectomy, 18% had postoperative radiotherapy, 51% had adjuvant hormone treatment and 47% received adjuvant chemotherapy. Survival of incident cases in 1993 to 2002 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 Caucasians were 58.6%, 89.6% and 88.3% respectively.