When it comes to rare cancers like medullary thyroid carcinoma (MTC), prognostic indicators often dictate treatment decisions and are therefore incredibly valuable. A study published in Cancers sought to establish the impact of advanced age on the clinical presentation and outcome of sporadic MTC.
MTC comes in either sporadic or hereditary form (the sporadic being the more common at 80%). The study is one of the first to look only at sporadic MTC.
MTC has an intermediate prognosis compared to other thyroid cancers, such as differentiated thyroid cancer (DTC), which carries a better prognosis, and anaplastic thyroid cancers (ATC), which has a poorer prognosis. While it is widely known that age plays a critical role in determining prognosis in hereditary MTC, little is known about the impact of age on sporadic MTC.
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Methodology and Results
In this study, researchers retrospectively evaluated the epidemiological, clinical, and pathological data of 530 consecutive sporadic MTC patients who were surgically treated and followed up at the Endocrine Unit of the Pisa University Hospital in Italy between 2000 and 2008. Patients who were followed for less than 2 years (n=98) were excluded, resizing the study population to 432 cases.
All the sporadic MTC patients who were included in the study had total thyroidectomy procedures performed. In addition, central compartment lymph node dissection was routinely performed in most of the patients, except in those in which it was incidentally discovered only after surgery. Patients with pre- or intra-operative evidence of latero-cervical lymph node metastasis had latero-cervical compartment lymph node dissection performed.
The authors of this study assessed the sex and age of each patient upon diagnosis, the pre-operative basal serum calcitonin levels, TNM stage, and other histologic features such as tumor size, presence of minimal extrathyroidal extension (mETE), and multifocality.
In this study, patients were separated into 2 groups: Group A, aged less than 65 years at the time of diagnosis, and Group B, aged 65 or more upon diagnosis.
Having separated the patients into 2 age categories, the authors of this study found:
- In the groups, the prevalence in the histological variants of MTC was the same (P =.2).
- There was no difference in the TNM staging between the groups, neither T stage (P =.92), N stage (P =.91), or M stage (P =.13).
- The prevalence of central and latero-cervical compartment lymph node dissection in both groups (87.6% vs 87.2%, P =.93 and 37.3% vs 34%, P =.56, respectively) was the same, setting the possible interference of the surgical treatment performed on the N result to zero.
- There was no difference between the groups in the type (P =.28) or prevalence (P =.22) of RET somatic mutations.
- Additional systemic and surgical local treatments were performed in the same percentage of patients in both groups.
- Although group B had a median follow-up that was recorded to be significantly shorter than group A (61 vs 96 months, P <.01), clinical outcomes were the same (P =.16).
- The Kaplan-Meier analysis showed a significant difference in the survival rate between the two groups [HR 2.5 (CI 95%: 1.27–4.94), P <.01], with the survival rate being higher in Group A.
- No significant difference in the potential effect of the aggressiveness of disease presentation in the patients who died in both groups during the course of the study.
- No statistically significant difference between both groups of the time elapsed between surgery and death for patients who died during the course of the study.
- Kaplan-Meier survival curves showed that group B had worse survival over time.
The authors of the study concluded that “MTC older patients (>65 years) showed a clinical presentation of the disease similar to the younger patients (<65 years). As far as cancer-related death events are concerned, the number of patients was similar in the two groups, but the time of survival was shorter in older patients as demonstrated by the Kaplan-[Meier] analysis.”
Read more about MTC prognosis
An Ever-Evolving Picture
This study represents another angle in our ever-evolving understanding of the impact of age on MTC prognosis. Previous studies that have looked at prognostic indicators for MTC (both sporadic and hereditary) have found that age played a more significant role in predicting outcomes.
For example, a study published in Cancer in 2006 looked at all patients diagnosed with MTC that had an active follow-up in the SEER database from 1973 to 2002. The authors of the study identified 1252 patients over the 29 years of follow-up. In multivariate analysis, the results show that stage of disease and age of diagnosis were the strongest predictors of survival.
In this study, researchers found that patients aged 65 years and older and those with advanced disease had a poor prognosis and that patients who underwent surgical intervention fared better than those who did not.
These conflicting studies on the impact of age on MTC prognosis mean that further studies are warranted. The authors of the second study put it best: “Despite technological advances in diagnostic modalities, refinement of imaging techniques, and the development of genetic screening over the last decade, to our knowledge there has been no survival improvement over nearly 30 years of treatment for MTC.” At present, early detection and surgical intervention seem to be the best measures to achieve better patient outcomes.
References
Matrone A, Gambale C, Prete A, et al. Impact of advanced age on the clinical presentation and outcome of sporadic medullary thyroid carcinoma. Cancers. 2021;13(1):94. doi: 10.3390/cancers13010094
Roman S, Lin R, Sosa JA. Prognosis of medullary thyroid carcinoma. Cancer. 2006;107(9): 2134-2142. doi:10.1002/cncr.22244
