The overall survival rate of papillary thyroid cancer is fairly high; however the latest research suggests that a recurrence is possible decades later — well after primary treatment has been completed — and is associated with a higher mortality rate.
The research results were presented at the American Association of Endocrine Surgeons 2013 Annual Meeting by researchers from the University of Texas MD Anderson Cancer Center, University of Chicago Medicine, and other renowned research institutes. Dr. Elizabeth G. Grubbs from MD Anderson commented:
“Being able to capture those important outcomes, which are relatively rare, takes a diligent long-term study… It’s valuable information.”
In the meeting, researchers provided the data indicating a median follow up time of 27 years according to the results of research cohort of 269 PTC patients. Assistant professor of surgery at University of Chicago Medicine, Raymon H. Grogan, suggested that the total number of cases of papillary cancer of thyroid cancer are rising, but since the prognosis of the disease is fairly good, recurrence after primary therapy is possible, warranting long term follow-ups. These findings are in contrast to the 3 most popularly cited studies on PTC, suggesting median follow-up times of 11, 15, and 15.7 years.
Dr. Grubbs added:
“What’s important from the study in my mind is that some of these recurrences and events happen many years out, so there isn’t a time frame where you say you don’t need to follow people or worry any more. This helps us in our understanding of how we need to follow these patients as clinicians and how we need to counsel patients.”
Essentials of the study:
Dr. Grogan reported data with a median follow up of 11 years, which was first presented in 1990. The patients were diagnosed at his institution during 1968 and 1988, suggesting a 5-year survival rate of 95%, 10- year survival rate of 94.7%, 20-year survival rate of 92%, 30-year survival rate of 91%, and 86% at 40 years. After the first 10 years of post-diagnosis, the cause of death in most patients are systemic disorders and not the cancer itself, suggesting a good prognosis of papillary thyroid cancer.
The rate of recurrence was fairly high in 269 PTC patients, calculated as 16% at 5 years, 20% at 10 years, 27% at 20 years, 30% at 30 years, and 33% at 40 years, with the highest recurrence rate (68%) and highest mortality rate (58%) during the first decade. Almost 17% of all PTC deaths occur 20 years after primary diagnosis and recurrence of cancer in 11% cases.
Upon analysis, it can be concluded that factors like older age at diagnosis, positive lymph nodes and early metastasis are the factors that are associated with early death. Similarly, follicular variants (as opposed to classic papillary thyroid cancer), size of the tumor, positive lymph nodes and metastasis are associated with higher mortality.
Factors like total thyroidectomy, radioactive iodine therapy and gender does not affect recurrence or survival significantly. Dr. Grogan suggested that all OTC patients should be followed throughout their lives to detect early recurrence in order to institute prompt treatment.