In a real-world study of the use of immune checkpoint inhibitors , approximately half of patients with advanced cancers developed thyroid dysfunction related to the cancer treatment within about a year; however, most cases were mild and were even associated with an increase in overall survival.
The association between ICIs and immune thyroid dysfunction has been consistently reported. However, most data detailing the effects come from pharmaceutical clinical studies that involved carefully screened participants.
In the study, the incidence of thyrotoxicosis caused by ICIs was significantly lower than that of hypothyroidism, mainly because thyrotoxicosis occurs before hypothyroidism in immune thyroid dysfunction caused by ICIs and can eventually evolve into hypothyroidism,"and therefore cases of thyrotoxicosis may be missed in some clinical studies," the authors observe.
Overall, thyroid dysfunction cases were mild. The vast majority were of grade 1 or 2. The incidence of grade 3 thyroid dysfunction was 4.2%, and there were no thyroid-related adverse effects of grade 4 or higher. It has been speculated that the improvement in survival is indicative of ICI activity, the authors note.