Clinical Evolution of Sporadic Medullary Thyroid Carcinoma With Biochemical Incomplete Response After Initial Treatment

Abstract

Context The clinical response after surgery is a determinant in the management of patients with medullary thyroid carcinoma (MTC). In case of excellent or structural incomplete response, the follow-up strategies are well designed. Conversely, in case of biochemical incomplete response (BiR) the management is not clearly defined. Purpose To evaluate the overall and per-site prevalence of structural disease detection in sporadic MTC patients with BiR and to assess the predictive value of various clinical, biochemical, and genetics features. Methods We evaluated data of 599 consecutive patients surgically treated for sporadic MTC (2000-2018) and followed-up at Endocrine Unit of the University Hospital of Pisa. Results After a median of 5 months from surgery, 145/599 (24.2%) patients were classified as BiR. Structural disease was detected in 64/145 (44.1%), after a median time of 3.3 years. In 73.6% structural disease was detected at a single site, prevalently cervical lymph nodes. Among several others, at the time of first evaluation after surgery, only basal calcitonin (bCTN) and stage IVa/b were independent predictive factors. Also, structural disease was more frequent in patients with shorter CTN doubling time and somatic RET mutation. Conclusions In sporadic MTC patients with BiR the risk of detection of structural disease was about 50% at 10 years. Higher bCTN levels and staging predicted the risk of detecting structural disease. According to these findings, a stricter follow-up should be reserved to MTC with BiR and elevated values of bCTN and to those with an advanced stage. Long follow-up should anyway be considered for all BiR patients since 50% of them develop structural disease within 10 years.

Timing and Ideal Patient for an Appropriate Search for Somatic RET Mutation in Medullary Thyroid Cancer

“…At the first postoperative evaluation (median 5 months [IQR, [3][4][5][6][7][8] from surgery), 356 of 651 (54.6%) patients were classified as ER and 128 of 651 (19.7%) patients already had a structural disease diagnosed either before or early after surgery and were classified as SiR. Finally, 167 of 651 patients, which accounts for 25.7%, met the clinical and biochemical criteria for classification as BiR (Fig 1A).…”

“…It is worth noting that about 24% of them required further treatments mainly local and only 7.8% required a systemic therapy. Recently, we reported data about 145 patients with sporadic MTC with BiR after initial therapy, 8 and in 44.1% of them, structural disease was detected after a median follow-up time of 3.3 years. Interestingly, 51.2% of patients with structural disease detection showed distant metastasis regardless of the simultaneous presence of lymph node metastasis.…”