A study of HTLV‐I infection and breast cancers in Trinidad and Tobago

The human T-cell lymphoma/leukaemia virus (HTLV-I), the first human retrovirus to be discovered, causes lymphoma/ leukaemia. Viruses may also be associated with a number of cancers, including liver, cervical and nasopharyngeal tumours. One viral model for breast cancer is the mouse mammary tumour virus (MMTV), a retrovirus which gives rise to a significant incidence of mammary cancer even in mice fosternursed on virus-free strains to eliminate maternal transmissions (Coffın, 1982). Several lines of research support the participation of MMTV in human breast cancer, but such evidence has been contradicted by further research. Clark et al. (1985), in a study to determine the prevalence of HTLV-I antibodies in individuals with various malignancies in Jamaica, observed HTLV-I seropositivity in 6 (27.3%) of 22 patients with breast cancer. This was higher but not statistically significant when compared with the age-matched population without malignancies in Jamaica. Our present study was conducted to determine whether there is any association between HTLV-I infection and the development of breast cancer in Trinidad and Tobago. Between June 1995 and September 1996, surveillance for cases of breast cancer was conducted by research nurses through visits to the National Oncology and Radiotherapy Centre in Port of Spain, and the wards and the pathology departments of the Port of Spain and San Fernando General Hospitals; 112 cases were recalled and enrolled. Cases of breast cancer were confirmed by histology. Thirty-two percent were infiltrating duct carcinoma, 29% invasive duct carcinoma, 12% adenocarcinoma and the remaining 27% lobular and papillary carcinoma. At enrollment, following written informed consent, a short questionnaire collecting demographic data was administered. Of the 112 cases enrolled, 111 were female and 1 was male. Age at diagnosis ranged from 25 to 89 years (mean 55 years). There were 78 (69.6%) individuals of African and mixed African descent, 30 (26.8%) of East Indian descent and 4 (3.6%) of other ethnic groups. Three (2.7%) of the 112 patients were HTLV-I ELISA– and Western blot–positive. Seropositive patients were females of African descent over 40 years of age (47, 69 and 75 years) at the time of diagnosis of the breast cancer. Since HTLV-I infection in Trinidad and Tobago occurs predominantly in Trinidadians of African origin (Blattner et al., 1990; Miller et al., 1986) and increases with age (Mueller et al., 1990), the HTLV-I prevalence by age of the breast cancer patients was compared with that of females of African descent in a 1986 general population HTLV-1 sero-survey in Trinidad. As shown in Table I, the overall HTLV-I seroprevalence of the women with breast cancer (3/78 or 3.8%) was not different from that of women in the general population sero-survey: 16/388 or 4.1% (p 5 0.8). There was also no significant difference in HTLV-I seropositivity between women older than 40 years among the general population and the breast cancer groups: 8.1% compared with 4.6% (p 5 0.6). In our study of 112 subjects in Trinidad and Tobago, there was no association of the retrovirus HTLV-I with breast cancer. Yours sincerely, Noreen JACK1, Jeffrey EDWARDS1, William DHANESSAR2, Hess BENJAMIN2 and Courtenay BARTHOLOMEW1*