Analysis of risk factors for cervical lymph node metastasis of papillary thyroid microcarcinoma: a study of 268 patients

BACKGROUND

To investigate the risk factors of cervical lymph node (LN) metastasis in papillary thyroid microcarcinoma (PTMC) patients.

METHODS

We retrospectively analyzed the clinicopathologic data of all patients who received standard lobectomy for PTMC at our institution between October 2017 and January 2019. Central LNs were dissected in all patients. Lateral LNs were dissected if metastasis to the lateral LNs was suggested based on pre-op fine-needle aspiration biopsy. The relationship between variables available prior to surgery and cervical LN metastasis was examined using multivariate regression.

RESULTS

Post-op pathologic examination revealed cervical LN metastasis in 79 (29.5%) patients. Seventy subjects had metastasis only to central LNs, and 4 (1.5%) patients had metastasis only to lateral LNs. Five patients had metastasis to both central and lateral LNs. In comparison to patients without cervical LN metastasis, those with LN metastasis were significantly younger (40.63 ± 13.07 vs. 44.52 ± 12.23 years; P = 0.021) and had significantly larger tumor diameter on pathology (6.7 ± 2.2 vs. 5.9 ± 2.4 mm; P = 0.010). Multivariate regression analysis identified the following independent risks for cervical LN metastasis: male sex (OR 2.362, 95%CI 1.261~4.425; P = 0.007), age (OR 0.977, 95%CI 0.956~0.999; P = 0.042) and ultrasound tumor diameter at > 5 mm (OR 3.172, 95%CI 1.389~7.240; P = 0.006).

CONCLUSION

Cervical LN metastasis occurs in a non-insignificant proportion of PTMC patients. Independent risks included male sex, younger age and larger tumor diameter on ultrasound.

Clinical and pathologic predictors of central lymph node metastasis in papillary thyroid microcarcinoma: a retrospective cohort study

OBJECTIVE

To identify the clinical and pathological predictors of central lymph node metastasis (CLNM) in patients with clinically lymph node-negative papillary thyroid microcarcinoma (PTMC).

MATERIALS AND METHODS

Data pertaining to 541 clinically lymph node-negative PTMC patients who underwent thyroid surgery at the Shanghai General Hospital between January 2010 and December 2013 were retrospectively analyzed. According to histopathological evidence of central lymph node involvement, patients were divided into central lymph node metastasis (CLNM)-positive and CLNM-negative groups; risk factors for CLNM were identified statistically.

RESULTS

LNM was found in 148 (27.4%) patients. Gender (P = 0.002), age (P < 0.001), tumor size (P < 0.001), multifocality (P < 0.001), and extrathyroidal extension (P < 0.001) were significantly different between CLNM-positive and CLNM-negative groups. On multivariate analyses, male sex (odds ratio [OR] = 2.656), age <45 years (OR = 4.184), tumor size >0.575 cm (OR = 2.105), gross extrathyroidal extension (OR = 14.605) and multifocality (OR = 2.084) were independent risk factors for CLNM. Among patients who did not have any of these five risk factors, only 3.9% were found to have CLNM.

CONCLUSIONS

A relatively high prevalence of CLNM was observed in patients with clinically lymph node-negative PTMC. CLNM was associated with male sex, younger age, larger tumor size, extrathyroidal extension and multifocal PTMC.

Differences in the recurrence and mortality outcomes rates of incidental and nonincidental papillary thyroid microcarcinoma: a systematic review and meta-analysis of 21 329 person-years of follow-up

CONTEXT

There is controversy as to whether papillary thyroid microcarcinoma (PTMC) represents more than one disease entity with different outcomes, requiring different treatment.

OBJECTIVES

To compare characteristics, outcomes, and factors associated with prognosis of incidental and nonincidental PTMC.

SETTING AND DESIGN

Two reviewers performed searches of online databases (1966-2012), reference lists, and conference abstract books. Longitudinal studies of subjects >16 years old receiving any treatments for papillary thyroid cancer ≤10 mm in size were included. Two reviewers independently screened abstracts and articles, extracted data, and assessed quality of studies using National Institute of Clinical Excellence and PRISMA criteria.

RESULTS

Of 1102 abstracts identified, 262 studies were reviewed and 17 studies included, comprising 3523 subjects, with mean follow-up of 70 months and total follow-up of 21 329 person-years. This included 854 subjects with incidental PTMC (follow-up, 4800 person-years; mean tumor size, 4.6 mm [range 3.3-6.7 mm]) and 2669 nonincidental PTMC cases (follow-up, 16 529 person-years; mean tumor size, 6.9 mm [range 5.6-8.0 mm]). The recurrence rate in the incidental group (0.5%; 95% confidence interval [CI], 0-1%, P < .001) was significantly lower than that in the nonincidental group PTMC (7.9%; 95% CI, 5-11%), with an OR of recurrence of 14.7 (95% CI, 5.6-54.8, P < .001) for nonincidental PTMC, compared with incidental PTMC. Lymph nodes were involved in 80% (126/157) of recurrences. On meta-regression, age, sex, size, tumor multifocality, lymph node involvement, and treatment modality were not significantly associated with recurrence.

CONCLUSIONS

Our meta-analysis strongly suggests the existence of at least two distinct entities of PTMC. Incidental PTMC has different clinical characteristics and a much lower recurrence rate than nonincidental PTMC, suggesting that management protocols should be re-considered. Additional studies with standardized data collection are required to explore potential differences between subgroups of nonincidental PTMC.

The Surgical Management of Papillary Thyroid Microcarcinoma: A 162-Month Single-Center Experience of 273 Cases

The aim of this study was to evaluate outcomes for patients with papillary thyroid microcarcinoma (PTMC) treated at a single institution during a 162-month period and to determine which patients need aggressive treatment. Two hundred seventy-three patients with PTMC had subtotal or total thyroidectomy 1 prophylactic or therapeutic lymph node dissection. Clinical and histopathological characteristics of 273 patients were identified and statistically analyzed. The tumors were multifocal in 36.3 per cent of the patients with PTMCs. Fifty-six per cent had neck lymph node metastases at diagnosis. Large-sized tumor (over 5 mm), age older than 45 years, multifocality, bilaterality, and extrathyroidal extension were associated with subclinical central lymph node metastases. Ninety-six patients older than 45 years of age were upgraded from Stage I to III or IVA. Ten patients with lateral node recurrence or local recurrence in the residual thyroid had one or more risk factors. The high rates of multifocality and Level VI area subclinical lymph node metastasis were two important clinical and histopathological characteristics of PTMC. Patients who had one or more risk factors should receive more aggressive surgical management.