Association of multifocality, tumor number, and total tumor diameter with clinicopathological features in papillary thyroid cancer

Abstract

Tumor multifocality is not an unusual finding in papillary thyroid carcinoma (PTC), but its clinical significance is controversial. In this study, we aimed to evaluate impact of multifocality, tumor number, and total tumor diameter on clinicopathological features of PTC. Medical records of 912 patients who underwent thyroidectomy and diagnosed with PTC were reviewed retrospectively. Patients were grouped into four according to number of tumoral foci: N1 (1 focus), N2 (2 foci), N3 (3 foci), and N4 (≥4 foci). The diameter of the largest tumor was considered the primary tumor diameter (PTD), and total tumor diameter (TTD) was calculated as the sum of the maximal diameter of each lesion in multicentric tumors. Patients were further classified into subgroups according to PTD and TTD. Multifocal PTC was found in 308 (33.8 %) patients. Capsular invasion, extrathyroidal extension, and lymph node metastasis were significantly higher in patients with multifocal tumors compared to patients with unifocal PTC. As the number of tumor increased, extrathyroidal extension and lymph node metastasis also increased (p = 0.034 and p = 0.004, respectively). The risk of lymph node metastasis was 2.287 (OR = 2.287, p = 0.036) times higher in N3 and 3.449 (OR = 3.449, p = 0.001) times higher in N4 compared to N1. Capsular invasion, extrathyroidal extension, and lymph node metastasis were significantly higher in multifocal patients with PTD ≤10 mm and TTD >10 mm than unifocal patients with tumor diameter ≤10 mm (p < 0.001, p < 0.001 and p = 0.001, respectively). There was no significant difference in terms of these parameters in multifocal patients with PTD ≤10 mm and TTD >10 mm and unifocal patients with tumor diameter >10 mm. In this study, increased tumor number was associated with higher rates of capsular invasion, extrathyroidal extension, and lymph node metastasis. In a patient with multifocal papillary microcarcinoma, TTD >10 mm confers a similar risk of aggressive histopathological behavior with unifocal PTC greater than 10 mm.

Therapeutic Outcomes of Patients with Multifocal Papillary Thyroid Microcarcinomas and Larger Tumors

“…Although the mean tumor size of the largest multifocal tumor was smaller than that in the solitary PTC group, the clinical and TNM stages were more advanced. In contrast to that in a recent study, the multifocal group in our study had a higher nonremission rate and a lower percentage of patients were disease-free when compared to the solitary PTC group [14]. These discordant results may due to the larger number of patients enrolled and the longer follow-up period in our study.…”

Independent predictors and lymph node metastasis characteristics of multifocal papillary thyroid cancer

“…[ 16 ] In present study, multifocality was associated with higher rates of disease recurrence and poorer prognosis compared with unifocal disease, in accordance with previous studies. [ 6 , 17 ] Multifocality has been reported in 18% to 87% of patients with PTC [ 10 ] and was observed in 22.8% of the patients in our center in 2015. The incidence of lymph node involvement solitary PTC is approximately 50%.…”

“…[ 9 ] The reported prevalence of multifocal PTC ranges from 18% to 87% depending on epidemiological and methodological factors. [ 10 ] It is well-established that PTC has a strong predilection for lymph node metastasis, most commonly to the central neck compartment (level VI) which are bordered by the hyoid bone superiorly, suprasternal notch inferiorly, and the carotid sheaths laterally. [ 11 ] Approximately, 30% to 90% of patients with PTC will have clinical or occult cervical lymph node involvement.…”

The occurrence of and predictive factors for multifocality and bilaterality in patients with papillary thyroid microcarcinoma

“…The prevalence of multifocal PTC, in which multifocality is one of its most characteristic features, depends on epidemiological and methodological factors and ranges from 18% to 87%. [9] However, regardless of its prevalence, the multifocality and bilaterality of PTC might easily go undetected by presurgical evaluations, such as ultrasonography and subsequently ultrasound guided-fine needle aspiration biopsy (UG-FNAB); thus, partial thyroid resections for cases of bilateral PTC may lead to the necessity of reoperation. [10] So et al [10] highlighted that additional PTMC foci are very often too small to be diagnosed before surgery, especially under the current guidelines on ultrasound screening evaluations for PTC.…”