Second primary breast and thyroid cancers (Israel).
OBJECTIVE
To evaluate the risk for developing second primary thyroid cancer (TC) following breast cancer (BC) and second primary BC following TC on a nationwide basis.


METHODS
All BC and TC Jewish females diagnosed in Israel during 1960-1998 were identified through the Israel Cancer Registry. The expected second primaries were calculated using cancer incidence rates stratified by age, country of birth and period of diagnosis among the Jewish population in Israel. Standardized incidence ratios (SIRs) were estimated using Poisson regression.


RESULTS
A total of 49,207 breast and 4911 thyroid neoplasms were identified. After the exclusion of concomitant disease (diagnosed within 1 year), 59 and 70 second primaries TC and BC yielded SIRs of 1.34 (95% CI: 1.03, 1.72) and 1.07 (95% CI: 0.84, 1.34), respectively. Younger age and earlier calendar year of first primary diagnosis and shorter follow-up period were associated with increased risk for developing second primary neoplasm.


CONCLUSIONS
Considering the long latency required for carcinogenesis, excess risk of second primary diagnoses soon after the first cancer, argues against the hypothesis of first primary treatment as an initiator for the second cancer. A detection bias of meticulously followed cancer patients, early exposure to common risk factors or genetic susceptibility of certain subpopulations for both malignancies seem plausible.
Sadetzki
Siegal
S
Cancer Epidemiology Unit, Gertner Institute, Chaim Sheba Medical Center, Tel Hashomer, Israel. siegals@gertner.health.gov.il
Calderon-Margalit
Ronit
R
Peretz
Chava
C
Novikov
Ilya
I
Barchana
Micha
M
Papa
Moshe Z
MZ
D000328:Adult; D017677:Age Distribution; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007557:Israel; D007585:Jews; D008875:Middle Aged; D016609:Neoplasms, Second Primary / Q000209:etiology; D012189:Retrospective Studies; D012307:Risk Factors; D013964:Thyroid Neoplasms / Q000453:epidemiology / Q000209:etiology