F. De Vathaire

Second primary malignancies in thyroid cancer patients

The late health effects associated with radioiodine (131I) 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 131I. 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 131I administered, with an excess absolute risk of 14.4 solid cancers and of 0.8 leukaemias per GBq of 131I and 105 person-years of follow-up. A relationship was found between 131I administration and occurrence of bone and soft tissue, colorectal, and salivary gland cancers. These results strongly highlight the necessity to delineate the indications of 131I treatment in thyroid cancer patients in order to restrict its use to patients in whom clinical benefits are expected.

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

SummaryThe 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.

Cardiac abnormalities 15 years and more after adriamycin therapy in 229 childhood survivors of a solid tumour at the Institut Gustave Roussy

The purpose of this paper was to determine the cardiac status in children 15 years or more after adriamycin therapy for a solid tumour. Of the 447 pts, 229 pts were fully studied and 218 were not. The following cardiac evaluations were proposed to all the 447 consecutive patients (pts): (1) cardiac Doppler US by one of two expert cardiologists; (2) cardiac rhythm and conduction abnormalities including 24-hour holter ECG; (3) 131l-mlBG myocardial scintigraphy; (4) serum brain natriuretic peptide levels at rest; (5) an exercise test with VO2 max measurement. The radiation doses delivered to 6 points in the heart were estimated for all patients who had received radiotherapy. Congestive heart failure was diagnosed in 24 of 229 (10%) evaluated pts, with a median interval of 15 years (0.3–24 years) from the first symptom after adriamycin treatment. Among the 205 remaining pts, 13 asymptomatic pts (6%) had severe (n=4) (FS<20%) or marked (n=9) (20⩽FS<25%) systolic dysfunction. In the 192 others, the median meridional end-systolic wall stress was 91 (53–135) and it exceeded 100 g cm−2 in 52 pts. Using a Cox model, only the cumulative dose of adriamycin and the average radiation dose to the heart, were identified as risk factors for a pathological cardiac status. In conclusion, the risk of cardiac failure or severe abnormalities increases with adriamycin treatment, radiotherapy and time since treatment, even after a follow-up of 15 years or more. In our series, after an average follow-up of 18 years, 39% of the children had a severe cardiac dysfunction or major ventricular overload conditions. The risk increases with the dose of adriamycin and radiation received to the heart, without evidence for threshold.

Leukaemias and cancers following iodine-131 administration for thyroid cancer.

We studied 1771 patients treated for a thyroid cancer in two institutions. None of these patients had been treated with external radiotherapy and 1497 had received (131)I. The average (131)I cumulative activity administered was 7.2 GBq, and the estimated average dose was 0.34 Sv to the bone marrow and 0.80 Sv to the whole body. After a mean follow-up of 10 years, no case of leukaemia was observed, compared with 2.5 expected according to the coefficients derived from Japanese atomic bomb survivors (P = 0.1). A total of 80 patients developed a solid second malignant neoplasm (SMN), among whom 13 developed a colorectal cancer. The risk of colorectal cancer was found to be related to the total activity of (131)I administered 5 years or more before its diagnosis (excess relative risk = 0.5 per GBq, P = 0.02). These findings were probably caused by the accumulation of (131)I in the colon lumen. Hence, in the absence of laxative treatment, the dose to the colon as a result of (131)I administered for the treatment of thyroid cancer could be higher than expected from calculation of the International Commission on Radiological Protection (ICRP). When digestive tract cancers were excluded, the overall excess relative risk of second cancer per estimated effective sievert received to the whole body was -0.2 (P = 0.6).

Estimation of the radiation dose delivered to any point outside the target volume per patient treated with external beam radiotherapy

The methodology we have developed to study dose distribution outside the target volume during external beam radiotherapy allows us to determine the dose received by the patient arising from leakage radiation and scattered radiation from both the head of the treatment machine and from the treatment room. It also allows us to evaluate the dose due to photon scattering in the patient by means of a dedicated 3-D algorithm permitting computations for the whole body of the patient and taking into account height, sex and anatomical data at the time of the treatment, dosimetric data and lung heterogeneity parameters. This methodology offers solid criteria for recommendations concerning radiation protection.

Role of radiotherapy and chemotherapy in the risk of second malignant neoplasms after cancer in childhood

Of a cohort of 634 children treated from 1942 to 1969 at the Gustave Roussy Institute for a first cancer and alive 5 years after treatment, 32 later developed second malignant neoplasms (SMN). A case-control study was performed to determine the relationship between the dose of radiotherapy received on a given anatomical site for the treatment of a first cancer, and the risk of SMN development at the same anatomical site. Another aim of the study was to analyse the effects of the association of radiotherapy with chemotherapy on the risk of SMN. The 32 cases of second malignant neoplasms were individually matched with one to nine patients of the cohort (a total of 162) who did not develop a SMN after a first cancer, matching on age, sex, type of first cancer and follow-up duration. The doses of radiotherapy delivered for the treatment of the first cancer were retrospectively estimated at the 26 anatomical sites of SMN. When the SMN was a leukaemia, the mean active bone-marrow dose was estimated as a weighted mean of the doses received by 20 bone sites. As compared to anatomical sites in children who had not received radiotherapy, the sites which had received 50 Gy or more had a relative risk of SMN of 5.8 (P less than 0.05). When taking into account the dose received at the site of the SMN, neither the number of fractions nor the type of radiations were related to the risk of SMN. Children who had received chemotherapy had a relative risk of SMN of 2.7 (95% CI: 1.2-6.4), adjusted for the dose of radiotherapy, as compared to those who had not. The relative risk of SMN did not vary with the dose nor the duration of the chemotherapy. Dactinomycin was found to increase the relative risk of second soft tissue and bone sarcomas. Cyclophosphamide was found to be less carcinogenic than the other alkylants. The relative risk of SMN was equal to 2.0 (n.s.) after radiotherapy of more than 25 Gy, to 4.4 (n.s.) after chemotherapy, and to 21.4 (P less than 0.01) after the combination of these two treatments modalities, as compared to patients treated by surgery alone. This study suggests that the oncogenic effect of radiations might be increased by chemotherapy, and that the combination of the two treatment modalities might be one of the major factors responsible for overall risk of SMN.

Combined hormone replacement therapy and risk of breast cancer in a French cohort study of 3175 women

The largest-to-date randomized trial (Womens Health Initiative) comparing the effects of hormone replacement therapy (HRT) and a placebo concluded that the continuous use of an oral combination of conjugated equine estrogens (CEE) and medroxy-progesterone acetate (MPA) increases the risk of breast cancer. This conclusion may not apply to women taking other estrogen and progestin formulations, as suggested by discrepancies in the findings of in vitro studies, epidemiological surveys and, mostly, in vivo studies of human breast epithelial cell proliferation showing opposite effects of HRT combining CEE plus MPA or estradiol plus progesterone. To evaluate the risk of breast cancer associated with the use of the latter combination, commonly prescribed in France, a cohort including 3175 postmenopausal women was followed for a mean of 8.9 years (28 367 woman-years). In total, 1739 (55%) of these women were users of one type of estrogen replacement with systemic effect during at least 12 months, any time after the menopause, and were classified as HRT users. Among them, 83% were receiving exclusively or mostly a combination of a transdermal estradiol gel and a progestin other than MPA. Some 105 cases of breast cancer occurred during the follow-up period, corresponding to a mean of 37 new cases per 10 000 women/year. Using multivariate analysis adjusted for the calendar period of treatment, date of birth and age at menopause, we were unable to detect an increase in the relative risk (RR) of breast cancer (RR 0.98, 95% confidence interval (CI): 0.65-1.5) in the HRT users. The RR of breast cancer per year of use of HRT was 1.005 (95% CI 0.97-1.05). These results do not justify early interruption of such a type of HRT, which is beneficial for quality of life, prevention of bone loss and cardiovascular risk profile, without the activation of coagulation and inflammatory protein synthesis measured in users of oral estrogens.

Radiation dose, chemotherapy, hormonal treatment and risk of second cancer after breast cancer treatment

In total, 281 of the 7711 women who were initially treated for breast cancer between 1954 and 1983 at the Gustave Roussy Institute developed a second malignant neoplasm (SMN) other than second primary breast cancer and nonmelanoma skin cancer at least 1 year after breast cancer treatment. We carried out a nested case–control study to determine the overall relationship between the dose of radiotherapy received at a given anatomical site and the risk of SMN at the same site. In total, 75% of the cases of SMN were previously treated by radiotherapy, as compared to 73% of the controls. In the irradiated patients, the median local dose was higher among cases (3.1 Gy) than among controls (1.3 Gy). More than 40% of the irradiated patients received a local dose of less than 1 Gy. A purely quadratic relationship was observed between the dose of radiation received at an anatomical site and the risk of SMN at this site. According to the quadratic model, the excess risk of SMN was 0.2% (95% CI 0.05–0.5%) when the target organ received 1 Gy. This risk did not differ significantly according to age at the time of radiotherapy (<40 vs ⩾40 years). The risk of SMN was 6.7-fold higher for doses of 25 Gy or more than in the absence of radiotherapy. No carcinogenic effect of chemotherapy was observed and a dose–effect relationship between the length of tamoxifen treatment and SMN occurrence was found. This relationship was limited to endometrial cancers and did not modify the relationship with radiation dose. Our results suggest that high radiation doses slightly increase the risk of second malignancies after breast cancer.

Variations with time and age in the risks of solid cancer incidence after radiation exposure in childhood

The Japanese atomic bomb survivor incidence data set and data on five other groups exposed to ionizing radiation in childhood are analysed and evidence found for a reduction in the radiation-induced relative risk of cancers other than leukaemia with increasing time since exposure. Overall, reductions of 5.7-6.1 per cent per year of time since exposure are indicated, depending on the time at which the reduction is presumed to start, and all the reductions are statistically significant at the 5 per cent level. There is no significant heterogeneity in the speed of the reductions in relative risk with time by cohort, by cancer type, sex, or age at exposure group. There is a significant reduction of relative risk with increasing age at exposure, but adjustment for age at exposure does not markedly affect the time trends of relative risk. For all of the groups considered, there is a statistically significant increase in the excess absolute risk with increasing time since exposure. However, by contrast with the relative homogeneity of the time trends of relative risk, there is statistically significant heterogeneity by cancer type within the Japanese cohort (P = 0.05) and between the cohorts (P < 0.0001) in the speed of increase of the excess absolute risk with time since exposure.

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.