Clinico-pathological Characteristics And Therapic Strategy Of Bilateral Thyroid Carcinoma

Objective:Bilateral thyroid carcinoma is a special type of thyroid carcinoma,most of which belongs to papillary thyroid carcinoma. Bilateral thyroid carcinoma consists of two types including synchronous bilateral thyroid carcinoma and metachronous bilateral thyroid carcinoma; lymph node metastasis is the main metstatic form; lymph node dissection including central zone dissection and lateral compartment dissection is indicated for lymphadenopathy.We aimed in this study to analyze the clinico-pathologic characteristics of bilateral thyroid carcinoma and explore proper therapic strategy through the aspects below.(1) Analyze change of incidence and constitutions of bilateral thyroid carcinoma.(2) To discuss the risk factors of lymph node metastasis for bilateral papillary thyroid cancer.(3) To study the feasibility of the low-collar incision neck dissection which suits for bilateral carcinoma with lymph node metastasis based on its safety and impact on life quality.Methods:The present study is divided into three parts.In part one, clinical data of26cases of bilateral thyroid cancers from the year of1999were compared retrospective with130cases of their counterparts from the year of2009and so it was with the clinico-pathologic data of16cases from the year of1999and104cases from the year of2009.In part two, clinical and pathological data of177cases of bilateral papillary thyroid cancers from January,2008to December2009were analyzed.In part three,96patients who had undergone modified neck dissection between December2007and December2008were included in the study. We conducted a retrospective cohort study comparing33patients who had level V-A and cervical plexus preserved through low collar neck dissection to63patients whose level V-A and cervical plexus were removed during hockey stick neck dissection. The groups were compared based on metastatic and total lymph nodes gathered at each level, dissection related complications, local recurrence, distant metastasis, life quality and scar texture score.Results:1. There were26cases of bilateral thyroid cancers including16cases of synchronous bilateral thyroid cancers and10cases of metachronous bilateral thyroid cancers from the year of1999; There were130cases of bilateral thyroid cancers including104cases of synchronous bilateral thyroid cancers and26cases of metachronous bilateral thyroid cancers from the year of2009. There were2cases of bilateral micro-carcinoma (12.5%) and3cases of mono-lateral micro-carcinoma (18.8%) in the group of synchronous bilateral thyroid cancers in1999; There were28cases of bilateral micro-carcinoma (26.9%) and52cases of mono-lateral micro-carcinoma (50%) in its counterpart in2009.2.47.4%cases had central neck lymph node metastasis (CLNM) and39%cases had lateral neck lymph node metastasis (LLNM). Our univariate and multivariate analysis found diffuse pattern and lymphovascular invasion were independent risk factors for CLNM. Younger age (<45year of age) and larger size of the primary tumor (>1.5cm) were also associated with CLNM. Male gender, larger size of the primary tumor (>1.5cm), extra-thyroidal extension and CLNM were associated with LLNM.3cases (1.7%) had permanent hypoparathyroidism and no patients had recurrent laryngeal nerve injury due to inappropriate surgical operations.3. Sex, age, tumor status, operation extent were comparable between groups except the age. There were no statistical differences between groups in metastatic and total lymph nodes gathered at each level, dissection related complications, local recurrence and distant metastasis. Loss of sensation and shoulder or neck pain was more frequently experienced in the hockey stick group (p<0.05). Patients in the low collar group were more satisfied with the cosmetic appearances (p<0.05). Scar texture scores in low collar group were significant superior to those of hockey stick group (p<0.01).Conclusions:The constituent ratio of bilateral thyroid cancers had changed in the year of2009compared with that of1999which might be due to the general application of ultrasound and its improved accuracy.Knowledge of distribution pattern of bilateral papillary thyroid cancers would help to evaluate CLNN. We recommend prophylactic central lymph node dissection for patients with bilateral papillary thyroid cancers, especially those with risk factor for CLNM. Patients with risk factor for LLNM should be carefully evaluated and followed up.Low collar neck dissection is feasible and safe with excellent cosmetic results for eligible cases.