Increased risk of second cancers following breast cancer: role of the initial treatment.
OBJECTIVE
The risk of second primary malignancies (SMN) was studied in a cohort of 4,416 one-year survivors of a breast cancer. The role of the menopausal status and of the initial treatment modalities (surgery, radiotherapy, and chemotherapy) was investigated.


RESULTS
Excluding second primary breast cancer and non-melanoma skin cancer, a total of 193 (4.4%) patients developed a SMN between 1973 and 1992, compared with 136 expected (Standardised Incidence Ratio, SIR = 1.4, 95% CI (1.2-1.6)). No trend towards either an increase or a decrease was noted in the SIR with time after treatment (p = 0.2). The greatest increase in the relative risk concerned soft tissue cancers (SIR = 13.0, 95% CI: 6.8-22.3), followed by leukaemia (SIR = 3.1, 95% CI: 1.7-5.0), melanoma (SIR = 2.7, 95% CI: 1.4-4.8), kidney (SIR = 2.5, 95% CI: 1.2-4.5), ovary (SIR = 2.0, 95% CI: 1.2-3.1) and uterine tumours (SIR = 1.9, 95% CI: 1.4-2.5). The SIR was 3.0 (95% CI 1.8-4.7) in women under 40 at the time of the breast cancer, 1.9 (95% CI: 1.4-2.4) in those aged 40-49 and 1.2 (95% CI 1.0-1.4) in those aged 50 or more. In the 2,514 women who had received radiotherapy as initial treatment without chemotherapy, the SIR for all SMN was 1.6 (95% CI: 1.1-2.3) fold higher than in those who had not received radiotherapy as initial treatment.


CONCLUSIONS
In conclusion, this study confirms the increased risk of second malignancies in women treated for a breast cancer, and particularly in those who were younger at the time of treatment for breast cancer. Our results also suggest that radiotherapy may play a role in the onset of these second lesions.
Rubino
C
C
Unité de Recherche en Epidemiologie des Cancers de l'Institut National de la Santé et de la Recherche Médicale (U521), Institut Gustave Roussy, Villejuif, France.
de Vathaire
F
F
Diallo
I
I
Shamsaldin
A
A
Lê
M G
MG
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000532:radiotherapy*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005602:France / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008593:Menopause; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D016609:Neoplasms, Second Primary / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology; D011878:Radiotherapy / Q000009:adverse effects; D012307:Risk Factors; D016019:Survival Analysis; D013997:Time Factors