Older age marker may be a more appropriate predictor of prognosis in papillary thyroid cancer
Younger age at diagnosis is no longer a useful predictor of negative outcomes in the staging of patients with papillary thyroid cancer. Prognosis for survival in thyroid cancer does not drop until age 65 to 74 years, and those patients still have 92.0% survival.
Age at diagnosis has been used since the 1970s to determine the severity of thyroid cancers. When diagnosed in patients younger than 45 years, papillary thyroid cancers, which include affected lymph nodes, are designated as stage 1, while a cancer with the same presentation in a patient older than 45 years is stage 3. This is in agreement with the staging system of the TNM Classification of Malignant Tumors of the American Joint Committee on Cancer and the International Union Against Cancer.
“While this staging system was once accurate and effective, we are seeing that patients age 45 to 64 [years] have similar outcomes to those under age 45 years,” explained Jeffrey L. Miller, MD, co-director of the Thyroid Center at Thomas Jefferson University Hospital and lead researcher on the study. The research team set out to determine the scientific validity of using age 45 years and older at diagnosis as a power negative prognosticator.
A literature review found that this age marker was first set forth in a study in 1979, and that was followed by a paper in 1993 that reviewed 1,779 patients treated for papillary thyroid cancer from 1940 to 1989 to determine the variables most prognostic of mortality. Regarding age, the mortality curve seemed most pronounced in patients older than 60 years.
The research team used the Surveillance, Epidemiology and End Result (SEER) database to analyze thyroid cancers diagnosed between 2001 and 2007 and to review 5-year survival rates. They reviewed 45,390 cases and found that the most significant drop in survival occurred in those age 65 to 74 years, and those patients still had a good prognosis of 92.0%. An even more marked survival difference occurred in patients with a thyroid cancer diagnosis at age 75 years and older, whose survival was 82.2%.
“With time, we have developed new therapies and surgical techniques, leading to better survival rates,” stated Miller. As a result, many patients will have a more favorable prognosis, avoid undergoing potentially unnecessary therapies, and have their fears about longevity allayed up to age 64 years. Miller added, “We feel that age 45 [years] is no longer an appropriate age designation to influence papillary thyroid cancer prognosis.”These findings were presented at the American Thyroid Association's annual meeting in Quebec City, Quebec, Canada.