Regular ultrasound surveillance of the thyroid revealed that about 7% of adult childhood cancer survivors who had radiation to the head or neck subsequently developed thyroid cancer.
Regular ultrasound surveillance of the thyroid revealed that about 7% of adult childhood cancer survivors who had radiation to the head or neck subsequently developed thyroid cancer, according to the results of a single-center Italian study published in the European Journal of Cancer.
“The histologic features of carcinomas diagnosed in our cohort suggest that, in the specific context of childhood cancer survivors, the use of ultrasound for early diagnosis of radiation-induced thyroid cancer may be suitable,” wrote Enrico Brignardello, of CittÃ della Salute e della Scienza Hospital, Turin, Italy, and colleagues.
According to the study, previous research has shown that radiation to the head, neck, or upper thorax at a young age is associated with an increased risk for developing thyroid cancer later in life. Currently, it is recommended that these survivors be screened with annual palpation of the thyroid.
“Although the sensitivity of neck palpation to detect thyroid cancer is low, particularly in early stages, this approach is supported by the observation that radiation-induced thyroid carcinomas are usually well differentiated (ie, papillary and, less frequently, follicular), generally behaving non-aggressively and with excellent survival rates in adults as well as in children,” the researchers wrote.
However, they also noted that thyroid cancer induced by radiation is often more aggressive and there is currently no consensus on the appropriate surveillance in these patients. Therefore, in this study, Brignardello and colleagues reported the results of using routinely performed thyroid ultrasound in childhood cancer survivors.
The study included 197 survivors referred to their clinical from November 2001 to September 2014. All patients underwent ultrasound surveillance starting 5 years after radiation and repeated every 3 years if negative.
During the screening period, 74 survivors (37.5%) developed thyroid nodules and 35 went on to have fine needle aspiration. This ultrasound screening method found differentiated thyroid cancer in 14 patients (7.1%). The median time from radiation therapy to thyroid cancer diagnosis was 13.08 years.
Eleven patients had lesions that were suspicious or diagnostic of thyroid cancer. All of these patients ultimately underwent surgery where thyroid cancer was confirmed. In addition, nine patients with TIR3 cytology went on to have surgery because of their high risk from prior radiation therapy; cancer was diagnosed in three of them.
The researchers noted that 13 of 20 operated nodules were not palpable at the time of surgery. All of the cancers but one were papillary.
“Differentiated thyroid cancer (ie, papillary and, less frequently, follicular carcinoma) generally behave in a non-aggressive way, with excellent survival rates, and this is the reason why in general population ultrasound screening for thyroid cancer is not considered cost effective and should be avoided,” the researchers wrote. “Nevertheless, some evidence has suggested that radiation-induced thyroid cancers have more aggressive biological features, possibly due to RET gene rearrangements. Moreover, it has been recently reported that adolescents and young adults who develop thyroid cancer as a second malignant neoplasm have a significantly decreased overall survival compared to those with primary thyroid cancer.”