Tumors and Other Diseases Following Childhood X-Ray Treatment for Ringworm of the Scalp (Tinea Capitis)

Abstract

The objective of the study is to characterize the risk of tumors from radiation exposure to the head and neck. A cohort of 2,224 children given x-ray treatment and 1,380 given only topical medications for ringworm of the scalp (tinea capitis) during 1940-1959 have been followed up for a median of 39 y to determine tumor incidence. Follow-ups were by mail/telephone questionnaire, with 84-88% of the original cohort followed and with medical verification of diseases of interest. Sixteen intracranial tumors [7 brain cancers, 4 meningiomas, and 5 acoustic neuromas (vestibular schwannomas)] occurred in the x-irradiated group following an average brain dose of about 1.4 Gy, compared to 1 acoustic neuroma in the control group. The standardized incidence ratio (SIR) for brain cancer was 3.0 [95% confidence interval (CI): 1.3, 5.9]. Even though the dose to the thyroid gland was only about 60 mGy, 2 thyroid cancers were found in the irradiated group vs. none among controls, and 11 vs. 1 thyroid adenomas were found in the respective groups. Following an average dose of about 4 Gy to cranial marrow, 8 cases of leukemia (SIR = 3.2, CI: 1.5, 6.1) were observed in the irradiated group and 1 in the control group. There was also a suggestive excess of blood dyscrasias. There was no difference between the groups in the frequency of other cancers of the head and neck (excluding nonmelanoma skin cancer) or in total mortality.

Risks Associated with Low Doses and Low Dose Rates of Ionizing Radiation: Why Linearity May Be (Almost) the Best We Can Do

“…Although the doses to the thyroid gland in the Israeli tinea capitis study were low, averaging 90 mGy (range, 40 -500 mGy), they were very uncertain, and Ron et al (43) point out that only minor dosimetric adjustment in this cohort is required to make the ERR compatible with that in the other four studies. No significant thyroid cancer excess was observed in a much smaller U.S. group of patients given similar treatment (average thyroid dose, 60 mGy) (44), but the difference in risk estimates between this study and the comparable Israeli study was not statistically significant (44). Two Swedish studies of patients with skin hemangioma with low-dose and low dose rate exposures to radium 226 obtained risk estimates that were similar to those in the pooled analysis of Ron et al (43): an ERR per gray of 7.5 (95% CI: 0.4, 18.1) on the basis of an estimated mean thyroid dose of 120 mGy (45) and an ERR per gray of 4.9 (95% CI: 1.3, 10.2) on the basis of a mean dose of 260 mGy (46).…”

A Cohort Study of Thyroid Cancer and Other Thyroid Diseases after the Chornobyl Accident: Dose-Response Analysis of Thyroid Follicular Adenomas Detected during First Screening in Ukraine (1998-2000)

“…Recently, we showed that the highest risk for thyroid cancer among those exposed to radioactive iodines was for the youngest age group (0-5 years) (6). Studies of benign neoplasia after irradiation showed contradictory evidence, with some studies exhibiting no effects of age at exposure (13,19) and others a strong inverse effect (10,12). We estimated the highest excess relative risk for follicular adenoma for those exposed at 5-10 years (excess relative risk ¼ 3.34 per gray), although risk estimates for three age categories were not significantly different (p ¼ 0.60).…”

Central nervous system tumours in children: Epidemiology and risk factors

“…Little evidence exists to demonstrate that diagnostic X-ray exposure during childhood is a risk factor but therapeutic doses of X-rays have been associated with raised risks [Kuijten and Bunin, 1993]. The now-discontinued low dose radiation treatment of tinea capitis and skin disorders in children increases the risk of CNS tumours well into adulthood [Shore et al, 2003], as does radiotherapy for childhood cancers and leukaemia.…”