High Preponderance of BRAF V600E Mutation in Papillary Thyroid Carcinoma Among Filipinos: A Clinicopathologic Study

An Executive Summary of The Philippine Interim Clinical Practice Guidelines for the Diagnosis and Management of Well Differentiated Thyroid Cancer 2021

Objectives

Thyroid cancer is the most common endocrine cancer in the Philippines affecting primarily women in the reproductive age group. Considering the burden of thyroid cancer in the country, the Department of Health (DOH) called for the development of a national clinical practice guideline that would address patient needs, and aid physicians in clinical decision-making while considering therapeutic cost and availability in the local setting. The 2021 guidelines are aimed at providing optimal care to Filipino patients by assisting clinicians in the evaluation of thyroid nodules and management of well differentiated thyroid cancer.

Methods

A steering committee convened to formulate clinical questions pertaining to the screening and evaluation of thyroid nodules, surgical and post operative management of thyroid cancer, and palliative care for unresectable disease. A technical working group reviewed existing clinical guidelines, retrieved through a systematic literature search, synthesized clinical evidence, and drafted recommendations based on the ADAPTE process of clinical practice guideline development. The consensus panel reviewed evidence summaries and voted on recommendations for the final statements of the clinical practice guidelines.

Results

The guidelines consist of clinical questions and recommendations grouped into six key areas of management of well differentiated thyroid cancer: screening, diagnosis, surgical treatment, post operative management, surveillance, and palliative care.

Conclusion

The 2021 guidelines for well differentiated cancer could direct physicians in clinical decision making, and create better outcomes for Filipino patients afflicted with the disease. However, patient management should still be governed by sound clinical judgement and open physician-patient communication.

Characterization of mortality and high-risk characteristics of thyroid cancer in Filipinos using the California Cancer Registry

Introduction

Filipinos are the third largest Asian American subgroup and have the highest incidence of thyroid cancer among all races. To better understand this racial/ethnic disparity in thyroid cancer affecting Filipinos we analyzed the California Cancer Registry (CCR) data in Filipino thyroid cancer cases from 1988 to 2018.

Methods

97,948 thyroid cancer cases in California from 1988 to 2018 (until 2015 for Asian subgroups) were evaluated. We examined the case distribution by sex, age at diagnosis, race/ethnicity including Asian ethnic subgroups, histology, TNM stage, tumor size, lymph node involvement, lymphovascular invasion, and multifocality. We also looked at treatment data including surgery and radiation including radioactive iodine therapy. We calculated age-adjusted mortality rates (AAMR) for each major racial group and each Asian ethnic subgroup. Binary logistic regression was used to determine the likelihood of high-risk characteristics and treatment when comparing Filipinos to other racial/ethnic groups. Kaplan-Meier Estimate was performed to evaluate thyroid cancer survival across all race/ethnicities. Multivariate Cox proportion hazards regression was performed to evaluate mortality risk from all causes of death by race.

Results

There were 5,243 (5.35%) Filipino thyroid cancer cases in California from 1988 to 2018. Filipinos had the highest AAMR (1.22 deaths per 100,000) in 2015. Filipinos had a higher likelihood of Stage IV thyroid cancer compared with Non-Hispanic Whites, Non-Hispanic Blacks, Hispanics and nearly all Asian subgroups. Filipinos had a worse 5-year and 10-year overall survival (OS) than the combination of all other Asian/Pacific Islanders. Filipinos compared to Non-Hispanic Whites had significant mortality risk in overall and papillary thyroid cancer cases (Overall HR: 1.10, 95% CI 1.07-1.13, p < 0.0001, Papillary HR: 1.11, 95% CI 1.07-1.14, p < 0.0001) when adjusted for race/ethnicity, age, gender, socioeconomic status, and stage. When stratified by Charlson comorbidity score, Filipinos compared to Non-Hispanic Whites still had significant mortality risk (Charlson 0 HR: 1.07, 95% CI 1.02-1.11, p = 0.0017, Charlson 1+ HR: 1.07 95% CI 1.002-1.14, p = 0.0434).

Conclusions

Filipino thyroid cancer patients have higher incidences of high-risk pathological features and greater AAMR and mortality risk. These findings warrant further investigation into better understanding the connection between the greater incidence of high-risk characteristics and increased mortality in Filipinos.

Predictors of Response to Therapy Among Post Thyroidectomy Adult Filipino Patients with Papillary Thyroid Carcinoma Based on the 2015 American Thyroid Association Guidelines

Objective

To identify factors independently associated with incomplete response to therapy based on the 2015 ATA guidelines in surgically treated Filipino patients with papillary thyroid carcinoma (PTC).

Methodology

This is a retrospective cohort study of adults aged 21-74 years with papillary thyroid carcinoma (PTC) treated with surgery with or without radioactive iodine therapy (RAI) in Makati Medical Center from 2013 to 2017. We collected the following factors through a review of charts: age at diagnosis, gender, family history of thyroid cancer, date of surgery, tumor size, capsular/lymphovascular invasion, lymph node/distant metastases, stage, risk of recurrence, dose of post-surgical RAI therapy, initial post-treatment serum Thyroglobulin (Tg) and anti-Tg antibody levels (Negative Tg level: suppressed non-stimulated Tg <0.2 ng/mL or TSH-stimulated Tg <1 ng/mL; Positive Tg level: suppressed Tg ≥1 ng/mL or a TSH-stimulated Tg ≥10 ng/mL or rising anti-Tg antibody levels), thyroid stimulating hormone suppression, post-operative imaging studies and levothyroxine dose. Response to therapy was checked 6-24 months post-therapy.

Results

We analyzed a total of 115 patients with PTC who underwent thyroidectomy. Patients who had family history of thyroid cancer were less likely to have an incomplete or indeterminate response (p=0.045). None of the patients with excellent response had lymphovascular invasion. Having a positive Tg (p=0.001) and positive anti-Tg post-operatively (p<0.001) were strongly associated with incomplete or indeterminate response.

Conclusion

Patients who were positive for thyroglobulin and anti-thyroglobulin post-operatively were strongly associated with incomplete or indeterminate response to therapy in PTC.

Clinical presentation and survival outcomes of well-differentiated thyroid cancer in Filipinos

Background

Filipinos have higher recurrence rates compared to other racial/ethnic groups, which might suggest a higher propensity for aggressive disease. The goal of this study was to perform a population‐based analysis of disease extent at diagnosis and survival outcomes in Filipino patients with well‐differentiated thyroid cancer relative to other racial/ethnic groups.

Methods

The study cohort comprised adult patients with well‐differentiated thyroid cancer diagnosed between 2004 and 2015, identified in the California Cancer Registry. Rates of extrathyroidal extension, nodal metastasis, and distant metastasis were compared between Filipinos, Non‐Filipino Asians, and Non‐Asians using multilevel logistic regression models. Survival outcomes were compared using Cox regression models, utilizing a sequential modeling approach.

Results

Filipino ethnicity was associated with extrathyroidal extension (OR 1.35, 95% CI 1.11–1.63) compared with non‐Asians and non‐Filipino Asians. Filipino ethnicity was also associated with nodal metastasis (OR 1.32, 95% CI 1.18–1.46), and with worse OS (Hazard Ratio [HR] 1.45, 95% CI 1.20–1.75) and DSS (HR 1.51, 95% CI 1.12–2.04). After adjusting for demographic and clinical factors, Filipino ethnicity was no longer associated with OS (HR 1.03, 95% CI 0.84–1.25) or DSS (HR 0.93, 95% CI 0.68–1.28).

Conclusion

Filipino patients with thyroid cancer are more likely to present with locoregionally advanced disease compared with non‐Filipino Asians and non‐Asians. Furthermore, Filipino patients have worse survival outcomes compared with non‐Filipino Asians and non‐Asians. However, this appears to be driven by the higher rates of locoregionally advanced disease in Filipino patients.

An affordable immunohistochemical approach to estimate the prevalence of BRAFV600E in large cohort studies-establishing the baseline rate of BRAF mutation in an institutional series of papillary thyroid carcinoma from Thailand

Background

Papillary thyroid carcinoma (PTC) accounts for the majority of diagnoses of thyroid carcinoma. BRAF^V600E mutation is the most common genetic alteration in PTC, which has diagnostic and prognostic significance. The rate of BRAF^V600E mutation in PTC from Thailand has not been reported. Our purpose was to estimate the prevalence of BRAF mutation in a large institutional series using an affordable approach, which combined mutation-specific immunohistochemistry (IHC) with VE1 antibody and tissue microarray (TMA).

Methods

A total of 476 PTC cases plotted on TMA were employed for determining the mutation status in this study. The cancer tissue of initial 100 cases (pilot study) were analyzed for BRAF^V600E mutation by using both direct sequencing and VE1 immunostaining. For the subsequent PTC cases, VE1 IHC was used as an alternative to direct sequencing for the detection of mutation. Univariate and multivariate analyses were done to determine the association of clinicopathological variables with BRAF^V600E mutation.

Results

In the pilot study, VE1 IHC showed excellent analytical performance (κ=0.884) for detecting BRAF^V600E mutation in PTC TMA as compared to direct sequencing. The prevalence of BRAF^V600E in the whole cohort was 60.9% by using VE1 IHC. The mutation was commonly seen in tall cell (92.9%) and classic (70.2%) variants of PTC. Multivariate analysis (P<0.05) showed association of BRAF^V600E with histological type of tumor, extrathyroidal extension, and absence of Hashimoto's thyroiditis.

Conclusions

In conclusion, BRAF^V600E mutation was detected in 60.9% of Thai PTC and it was associated with several aggressive clinicopathological variables of thyroid cancer. VE1 IHC proved as a reliable method able to replace direct sequencing for detection of the mutation. A combination of mutation-specific IHC and TMA allows conducting large cohort studies more labor-saving and cost-efficiently.

Prevalence of BRAFV600E mutation in Asian series of papillary thyroid carcinoma-a contemporary systematic review

Papillary thyroid carcinoma (PTC), the most common malignancy of the endocrine system, is frequently driven by BRAFV600E mutation, which was reported in 35-60% cases in Western series. Numerous studies have recently emerged from Asian countries and regions; however sufficient summary is lacking to date. BRAF mutation serves as a diagnostic and prognostic tool in thyroid cancer, therefore establishing a rate of BRAF on the national scale could be of practical significance. We performed systematic reviews of available literature to investigate the prevalence of BRAF mutation in series of PTC from various Asian countries and regions. Out of the total 3,966 reports identified via initial screening, 138 studies encompassing over 40,000 PTCs were included for the final analysis. A vast majority (90.2%) of PTCs with known BRAF status were from East Asia, including China, South Korea, and Japan, with BRAF mutation rates of 71.2%, 75.5%, and 70.6%, respectively. Less abundant Indian and Saudi Arabian series found 45.6% and 46.3% prevalence of BRAFV600E in PTC, respectively. Much limited evidence was available from Thailand, Iran, Kazakhstan, Taiwan, Singapore, Indonesia, Hong Kong, Philippines, Vietnam, Iraq, and Myanmar. No relevant publications were found from other highly populated countries, such as Pakistan, Bangladesh, and Malaysia. After grouping by geographic region, we found that the highest rate of BRAFV600E was reported in the PTC series from East Asia (76.4%). Much lower rate (45-48%) was seen in PTC cohorts from South Asia, Central Asia, and the Middle East while the Southeast Asian series were in between (57%). Further subgroup analysis revealed that studies employing fresh frozen tissue and fine-needle aspirates showed higher rates of BRAF compared to those used formalin-fixed paraffin-embedded tissues. We found that the PTC series enrolled patients' cohorts after 2010 demonstrated a higher rate of BRAF compared to the earlier series. Finally, pediatric PTCs had lower BRAF prevalence compared to the baseline rate for the country. In conclusion, despite considerable among and within countries heterogeneity, the Asian PTC series showed a higher prevalence of BRAFV600E mutation than that in Western series. Causes of geographic heterogeneity, whether genuine (etiology, genetics) or methodology-related should be further investigated.