Change Cutoff to 55 Years in Staging for Thyroid Cancer

Roxanne Nelson BSN, RN

April 18, 2016

Changing the cut point for the American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) staging system for well-differentiated thyroid cancer (WDTC) from 45 years to 55 years may be warranted.

Findings from a large multicenter study, published in the March issue of Thyroid, showed that raising the age in the current AJCC/UICC staging system to 55 years would help avoid overtreatment in 12% of patients.

The move would be clinically relevant for thousands by preventing low-risk patients from overstaging. In addition, changing the cutoff would allow for more realistic estimates of prognosis in patients who remain at high risk, say the study authors.

Such a change would improve the distribution of outcomes between stage I and IV disease, commented senior author Jatin Shah, MD, Elliot W Strong Chair in Head and Neck Oncology at Memorial Sloan Kettering Cancer Center (MSKCC) in New York.

"Patients between the age of 45 and 55 with low-risk tumors are unnecessarily upstaged due to age and getting unnecessary aggressive treatment," explained Dr Shah.

"This shift will help avoid overtreatment and its complications/sequelae, by shifting them to a low-risk group, with relatively conservative treatment and equally good outcomes of treatment for the cancer," he told Medscape Medical News.

Growing Evidence Shows Age Cutoff Too Low in WDTC

Dr Shah and his international team explain that the biology of WDTC is highly dependent on age, with younger patients achieving better outcomes, and the AJCC/UICC includes age within its staging system.

All patients under the age of 45 years are currently considered to be stage I, unless there is evidence of distant metastases, which then moves it to stage II.

But for individuals 45 years and older, WDTC is categorized based on factors such as tumor characteristics, nodal involvement, and distant metastatic disease.

The authors point out that age 45 was selected as the cutoff age largely based on historical patient cohorts, but recent data suggest that the average age at diagnosis is rising. In turn, this trend puts more patients at risk of being placed in a higher-stage group.

In addition, growing evidence shows that that many older patients remain at low risk of disease-specific death, suggesting that the age cutoff is too low.

A recently published survival analysis of patients who were treated at MSKCC between 1986 and 2005 (Ann Surg Oncol. 2016;23:410–415) concluded that changing the age cutoff from 45 to 55 years in the current AJCC/UICC model would lead to a significant increase in the number of patients categorized into a lower stage while maintaining the excellent outcomes for patients considered to have early-stage WDTC.

Thus, the goal of the current paper was to validate this proposed change in age cutoff in a large patient population.

Validating the MSKCC Model

Dr Shah and colleagues evaluated a cohort of 9484 patients with WDTC, using data supplied by 10 institutions in the United States, Brazil, Canada, and Australia.

Tumor, nodes, and metastasis data, and age were provided for each patient, and the cohort was stratified by AJCC/UICC stage using age 45 years and age 55 years as cutoffs.

The median patient age was 45 years, and nearly half of the patients (49.1%) had T1 tumors, with most (69.7%) diagnosed as N0/NX.

The vast majority of the cohort did not have metastatic disease and were recorded as M0/MX (97.4%).

Patients were first staged with the AJCC/UICC system using 45 years as the age cutoff. There were 6600 patients (69.6%) reported as stage I, 741 patients (7.8%) as stage II, 1230 (13%) as stage III, and 913 (9.6%) as stage IV.

The same cohort was then staged using 55 years as the age cutoff. Stage I again comprised the largest group, with 7736 patients (81.5%). Stage II had the fewest number of patients (441; 4.6%), stage III had 707 patients (7.5%), and stage IV had 600 patients (6.3%).

A total of 1165 patients were downstaged (12.3%) by changing the cutoff age, and 329 patients (3.5%) went from stage II to stage I.

In addition, 523 patients (5.5%) were downstaged from stage III to stage I; 284 patients (3.0%) were downstaged from stage IV to stage I; and 29 patients (<1%) changed from stage IV to stage II.

Comparison With ATA Guidelines

For most endocrinologists and thyroid-cancer patients, however, the question of most importance is whether to administer postthyroidectomy radioactive iodine (RAI), said Keith C Bible, MD, PhD, a medical oncologist at the Mayo Clinic, Rochester, Minnesota.

"In such a context, if age is used as a determinant of stage, the proposed staging change has potential relevance," he said.

However, in the latest guidelines from the American Thyroid Association (ATA), there is no specific age cutoff or AJCC stage used in defining the advisability of RAI administration, explained Dr Bible, who was approached by Medscape Medical News for an independent comment.

"Age is mentioned in the text and in the table in citing published studies, highlighting the age controversy in terms of <45 or <55 cutoff, but a specific age is not proposed as a defining factor in RAI administration determinations.

"Hence, if one follows the new ATA guidelines, the current manuscript is of no substantial relevance — for the new guidelines have already taken into account the issues used to propose a staging change," Dr Bible noted.

However, he added that, as a patient, "it will be preferable to learn that you have stage II, rather than stage IV disease, so there is also the aspect of patient psychology to be considered."

This research was funded in part through the National Institutes of Health/National Cancer Institute. The authors no relevant financial relationships.

Thyroid. 2016;26:373-380. Abstract

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