Akira Miyauchi1. 1. Department of Surgery, Kuma Hospital, 8-2-35 Shimoyamate-dori, Chuo-ku, Kobe, Hyogo, 650-0011, Japan. miyauchi@kuma-h.or.jp.
Abstract
INTRODUCTION: The basic nature of cancer includes unlimited growth, invasion, and metastasis. The TNM staging system is very simple and popular. It indicates the degree of the anatomical spread of the disease but does not include tumor growth. Collins reported that human tumors grow exponentially, which can be expressed in doubling time. PATIENTS AND METHODS: We found that in patients with medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC) serum calcitonin and thyroglobulin levels changed exponentially over time, respectively, and that doubling times of these values were very strong prognostic factors. Doubling time has two major limitations. Doubling rate resolves these limitations. Using doubling rate, we performed kinetic analyses on tumor volume during active surveillance of micro-PTC. RESULTS: Our kinetic studies on patients with biochemically persistent disease revealed that 17% of MTC and 51% of PTC showed decrease in serum tumor marker levels over time. During active surveillance of micro-PTC, 17% of the patients showed clear decrease in their tumor volume. The evidences currently available are limited. However, our data indicate the following: Growth slowdown and regression are very common phenomena in the natural history of micro-PTC, clinical PTC in young and middle-aged patients, and hereditary MTC. The biologic characteristics of cancers of the same name, such as PTC, are diverse and vary widely with age. CONCLUSIONS: Doubling time and doubling rate are very powerful tools to provide the most appropriate management for the patients with thyroid cancers. Knowing the natural history of thyroid cancer is essential for the best disease management of thyroid cancer.
INTRODUCTION: The basic nature of cancer includes unlimited growth, invasion, and metastasis. The TNM staging system is very simple and popular. It indicates the degree of the anatomical spread of the disease but does not include tumor growth. Collins reported that human tumors grow exponentially, which can be expressed in doubling time. PATIENTS AND METHODS: We found that in patients with medullary thyroid carcinoma (MTC) and papillary thyroid carcinoma (PTC) serum calcitonin and thyroglobulin levels changed exponentially over time, respectively, and that doubling times of these values were very strong prognostic factors. Doubling time has two major limitations. Doubling rate resolves these limitations. Using doubling rate, we performed kinetic analyses on tumor volume during active surveillance of micro-PTC. RESULTS: Our kinetic studies on patients with biochemically persistent disease revealed that 17% of MTC and 51% of PTC showed decrease in serum tumor marker levels over time. During active surveillance of micro-PTC, 17% of the patients showed clear decrease in their tumor volume. The evidences currently available are limited. However, our data indicate the following: Growth slowdown and regression are very common phenomena in the natural history of micro-PTC, clinical PTC in young and middle-aged patients, and hereditary MTC. The biologic characteristics of cancers of the same name, such as PTC, are diverse and vary widely with age. CONCLUSIONS: Doubling time and doubling rate are very powerful tools to provide the most appropriate management for the patients with thyroid cancers. Knowing the natural history of thyroid cancer is essential for the best disease management of thyroid cancer.