Second primary malignancies in thyroid cancer patients

The late health effects associated with radioiodine ((131)I) given as treatment for thyroid cancer are difficult to assess since the number of thyroid cancer patients treated at each centre is limited. The risk of second primary malignancies (SPMs) was evaluated in a European cohort of thyroid cancer patients. A common database was obtained by pooling the 2-year survivors of the three major Swedish, Italian, and French cohorts of papillary and follicular thyroid cancer patients. A time-dependent analysis using external comparison was performed. The study concerned 6841 thyroid cancer patients, diagnosed during the period 1934-1995, at a mean age of 44 years. In all, 17% were treated with external radiotherapy and 62% received (131)I. In total, 576 patients were diagnosed with a SPM. Compared to the general population of each of the three countries, an overall significantly increased risk of SPM of 27% (95% CI: 15-40) was seen in the European cohort. An increased risk of both solid tumours and leukaemias was found with increasing cumulative activity of (131)I administered, with an excess absolute risk of 14.4 solid cancers and of 0.8 leukaemias per GBq of (131)I and 10(5) person-years of follow-up. A relationship was found between (131)I administration and occurrence of bone and soft tissue, colorectal, and salivary gland cancers. These results strongly highlight the necessity to delineate the indications of (131)I treatment in thyroid cancer patients in order to restrict its use to patients in whom clinical benefits are expected

Thyroid cancer following nuclear tests in French Polynesia

BACKGROUND: Between 1966 and 1974, France conducted 41 atmospheric nuclear tests in Polynesia, but their potential health effects have not previously been investigated. METHODS: In a case-control study, we compared the radiation exposure of almost all the French Polynesians diagnosed with differentiated thyroid carcinoma between 1981 and 2003 (n = 229) to the exposure of 373 French Polynesian control individuals without cancer from the general population. Radiation exposures were estimated using measurements after the nuclear tests, age at time of each test, residential and dietary information. RESULTS: The average thyroid dose before 15 years of age was about 1.8 mGy, and 5% of the cases and 3% of the controls received a dose above 10 mGy. Despite this low level of dose, and after adjusting for ethnic group, level of education, body surface area, family history of thyroid cancer and number of pregnancies for women, we observed an increasing risk (P = 0.04) of thyroid cancer with increasing thyroid dose received before age of 15 years, which remained after excluding non-aggressive differentiated thyroid micro-carcinomas. This increase of risk per unit of thyroid radiation dose was higher (P = 0.03) in women who later experienced four or more pregnancies than among other women. CONCLUSION: The risk estimate is low, but is based on limited exposure data. The release of information on exposure, currently classified, would greatly improve the reliability of the risk estimation. British Journal of Cancer (2010) 103, 1115-1121. doi: 10.1038/sj.bjc.6605862 www.bjcancer.com Published online 31 August 2010 (c) 2010 Cancer Research U

Second malignant neoplasms after a first cancer in childhood: temporal pattern of risk according to type of treatment

The variation in the risk of solid second malignant neoplasms (SMN) with time since first cancer during childhood has been previously reported. However, no study has been performed that controls for the distribution of radiation dose and the aggressiveness of past chemotherapy, which could be responsible for the observed temporal variation of the risk. The purpose of this study was to investigate the influence of the treatment on the long-term pattern of the incidence of solid SMN after a first cancer in childhood. We studied a cohort of 4400 patients from eight centres in France and the UK. Patients had to be alive 3 years or more after a first cancer treated before the age of 17 years and before the end of 1985. For each patient in the cohort, the complete clinical, chemotherapy and radiotherapy history was recorded. For each patient who had received external radiotherapy, the dose of radiation received by 151 sites of the body were estimated. After a mean follow-up of 15 years, 113 children developed a solid SMN, compared to 12.3 expected from general population rates. A similar distribution pattern was observed among the 1045 patients treated with radiotherapy alone and the 2064 patients treated with radiotherapy plus chemotherapy; the relative risk, but not the excess absolute risk, of solid SMN decreased with time after first treatment; the excess absolute risk increased during a period of at least 30 years after the first cancer. This pattern remained after controlling for chemotherapy and for the average dose of radiation to the major sites of SMN. It also remained when excluding patients with a first cancer type or an associated syndrome known to predispose to SMN. When compared with radiotherapy alone, the addition of chemotherapy increases the risk of solid SMN after a first cancer in childhood, but does not significantly modify the variation of this risk during the time after the first cancer. © 1999 Cancer Research Campaig