Risk Factors for Nonsynchronous Second Primary Malignancy and Related Death in Patients with Differentiated Thyroid Carcinoma

Abstract

BackgroundDifferentiated thyroid cancer (DTC) survivors are at increased risk of developing nonsynchronous second primary malignancy (NSPM). This study aims to examine possible risk factors leading to occurrence of NSPM as well as risk factors leading to NSPM-related death in patients with DTC.MethodsOf the 1,106 patients with DTC managed at our institution, 92 (8.3%) patients developed NSPM and 40 (3.6%) patients died of NSPM. All causes of death were confirmed by medical record, autopsy report or death certificate. Clinicopathological variables were compared between those without NSPM and with NSPM as well as between those who died of NSPM and did not die of NSPM. Significant variables on univariate analysis were entered into a Cox proportional hazards model.ResultsThe median latency period from diagnosis of DTC to NSPM was 142.7 (range 16.8–511.0) months. For occurrence of NSPM, age at DTC diagnosis ≥50 years old [relative risk (RR) = 2.35], cumulative radioactive iodine (RAI) activity 3.0–8.9 GBq (RR = 2.38), and external local radiotherapy (ERT) (RR = 1.95) were significant risk factors. For NSPM-related death, age at DTC diagnosis ≥50 years old (RR = 3.32) and nonbreast cancer (RR = 5.76) were significant risk factors.ConclusionsNSPM accounted for 18.7% of all deaths in DTC, but mortality was high (43.5%). Age at DTC diagnosis ≥50 years old, cumulative RAI activity 3.0–8.9 GBq, and ERT were significant risk factors for occurrence of NSPM, whereas age at DTC diagnosis ≥50 years old and the diagnosis of nonbreast cancer were significant risk factors for NSPM-related death.

Is prophylactic central neck dissection necessary for cN0 differentiated thyroid cancer patients at initial treatment? A meta-analysis of the literature

“…In accordance with previous results, we found that there was no significant difference between the two groups in terms of postoperative recurrence for patients who had adjuvant RAI. On the other hand, because of upstaging, it is expected that more patients would require RAI ablation and inevitably might be subjected to potential drawbacks from radiation, such as recurrent sialoadenitis, salivary gland swelling and increased risk of second primary malignancies in the long term 44 - 46 . Although RAI ablation is not recommended for patients with PTC in the absence of high-risk features according to the revised ATA guidelines 8 , studies have yet to clarify whether these upstaged patients are overtreated.…”

Second primary malignancies following thyroid cancer: a population-based study in Taiwan

“…Ishikawa et al (23) conducted a retrospective study of 3321 operated thyroid cancer patients between 1946 and 1985 in their institution and found a significant elevated risk for SPM in the CNS and respiratory organs. Lang et al (24,25,26) has shown the increased risk of SPMs among 1106 thyroid cancer patients, but only the occurrence of SPMs in breast and stomach was statistically significant. There is a clear need for another large-scale epidemiological study.…”

Nonoperative management of low-risk differentiated thyroid carcinoma

“…Hay et al [ 20 ] showed that total thyroidectomy and RAI ablation did not reduce recurrence, and Lang and Wong [ 21 ] demonstrated that RAI ablation increased the risk of second primary carcinoma. Other groups showed that BRAF V600E mutation can be a marker of aggressive characteristics and may require aggressive treatment [ 22 , 23 ], but there is no evidence that BRAF mutation affects the prognosis except for high-risk PTC patients in a Japanese population [ 24 , 25 ].…”