Rising incidence of breast cancer in Papua New Guinea

BACKGROUND: Three previous reports have shown the incidence of breast cancer in Papua New Guinea (PNG) to have risen in the 30 years between 1958 and 1987. In the present report the incidence and pathology of breast cancer in the decade 1989-1998 are described. METHODS: This was a retrospective review of all histopathology specimens in PNG from 1989 to 1998. During this period the female population grew from 1 640 000 to more than 2 000 000. RESULTS: There were 790 cases of breast cancer. The age of the patient was not known in 221 cases (26%). The age-standardized incidence was 6.9 per 100 000. The incidence of breast cancer has been steadily rising in the 40 years since cancers were recorded in PNG. The incidence has risen in all four regions, most notably in the islands. The peak incidence was in the 45-54-year-old age group (18.4/100 000); 83.9% of women with breast cancer were aged 54 or less. Fifteen per cent were under 35 years old and 55.7% were under 45. The incidence fell in the elderly. The tumours tended to be advanced. The actual size was recorded in only 163 cases (20.7%) but there were only three T1 tumours in this group. Clinical signs of advanced breast cancer were recorded in 206 cases: ulceration of skin (91 cases), peau d' orange (69 cases), nipple retraction (43 cases) and lymphoedema of the upper extremity (three cases). Axillary nodes were positive in 185 of 247 patients (75%) in whom they were sampled. CONCLUSIONS: The incidence of breast cancer in PNG women has steadily risen over the past 40 years and the highest age-specific incidence occurs in the 35-54 age group. Tumours present late at an advanced stage. Clinical information on pathology request forms is poor and a prospective clinical audit is needed. Strategies need to be developed to detect breast cancer earlier in this population of women.