Incidence of cancer in adolescent idiopathic scoliosis patients treated 25 years previously

Abstract

Purpose: To report the incidence of cancer in a cohort of adolescent idiopathic scoliosis (AIS) patients treated 25 years previously.

Methods: 215 consecutive AIS patients treated between 1983 and 1990 were identified and requested to return for clinical and radiographic examination. The incidence of cancer was determined through chart review and follow-up interviews. Using the original radiographic log file that included patient position, mAs, kV and the total number of X-rays taken, a radiation physicist calculated the total radiation dose during treatment and follow-up adjusted for BMI and sex.

Results: From the original cohort of 215 consecutive AIS patients, radiation information was available in 211 of the patients, and medical charts were available in 209 AIS patients. 170 (83 %) of the 205 AIS patients participated in the follow-up study with questionnaires. The calculated mean total radiation exposure was 0.8-1.4 mSV per examination and 2.4-5.6 mSv/year. An average of 16 radiographs were taken during the treatment period. Nine AIS patients developed cancer, mostly breast (3) and endometrial (4). The AIS patients had a relative risk of 4.8 (CI 2.3-5.8, p < 0.000) for developing cancer compared to the normal Danish population.

Conclusions: The overall cancer rate in this AIS cohort was 4.3 % which is five times higher than compared to the age-matched Danish population, and endometrial and breast cancer was most frequent. The radiation dose applied to the patients in this study, is comparable to modern equipment. This is to our knowledge the first study to report increased rates of endometrial cancers in a cohort of AIS patients, and future attention is needed to reduce the radiation dose distributed to the AIS patients both pre-operatively and during surgery.

Keywords: Adolescent idiopathic scoliosis; Incidence of cancer; Long-term follow-up; Radiation dose.