|
|
|
|
OJHAS: Vol. 5, Issue
4: (2006 Oct-Dec) |
|
|
|
Iodine and Thyroid Cancer in Goa |
|
Raman Arora
Junior
Resident, Goa Medical
College, Bambolim, Goa
Avril Dias
Associate
Professor, Department of
Pathology, Goa Medical
College, Bambolim, Goa |
|
|
| |
|
|
|
|
|
|
Address For Correspondence |
House No 305, Chandgi ram block,
Asiad village complex,
Delhi-110049, INDIA
E-mail:
drramanaiims@gmail.com |
|
|
|
|
|
Arora R, Dias A. Iodine and thyroid cancer in Goa
Online J Health Allied Scs.2006;4:3 |
|
|
|
Submitted: Feb 8,
2007; Suggested Revisions: Feb 14, 2007;
Revised: Mar 9, 2007; Suggested Revisions: Mar 20, 2007;
Revised: Mar 24, 2007; Accepted: Mar 26, 2007 |
|
|
|
|
|
|
|
| |
| |
| Abstract: |
|
There is a low
papillary to follicular ratio in iodine deficient areas. A study of malignant
thyroid tumors done over a period of 4 years in Goa shows that the ratio of
papillary to follicular carcinoma in Goa conforms to a iodine deficient status
of the population.
Key Words:
Iodine, Thyroid
carcinoma, Papillary, Follicular |
|
The most frequent endocrine malignancies are thyroid carcinomas accounting for
approximately 0.5–10 cases per 100,000 population.(1) The overall
incidence of thyroid carcinoma is generally not considered to be influenced by
iodine intake of a population whereas distribution of types of differentiated
thyroid carcinoma may be related to intake of iodine.(2) In areas of
iodine deficiency, relative frequency of follicular carcinoma is high, but overall,
papillary carcinoma remains higher and there is a low papillary to follicular
ratio in iodine deficient areas.
The study of malignant thyroid tumors was done over a
period of 4 years (2000-2003). All thyroid tumors were derived from unselected surgical material sent
to the department of Pathology, Goa medical college, Bambolim, Goa from the
department of Surgery
and various private surgeons. The thyroids of surgical material were
grossed and histological sections were prepared from every macroscopic lesion
suspected to be malignant. As necessary, additional sections of available material
were prepared and special stains employed, in particular congo red to identify medullary
carcinoma. Histological diagnosis was made on light
microscopic examination. WHO international classification was followed for typing
the thyroid malignant thyroid tumors.
Among 31815 specimens received over a period of 4 years,
620 were thyroid specimen and among them we found 66 malignant
thyroid tumors. Papillary carcinoma was most common (54.55%) of
all classified malignant thyroid tumors exceeding follicular (36.37%) and medullary (6.06%) lymphoma (1.51%) and anaplastic carcinoma (1.51%). The
papillary to follicular carcinoma ratio was 1.5:1.
Table 1: Histological classification of malignanty thyroid lesions
|
Histological Type |
Number of malignant thyroid
tumors |
% of total thyroid
malignancies |
|
Papillary carcinoma |
36 |
54.55% |
|
Follicular carcinoma |
24 |
36.37% |
|
Medullary carcinoma |
4 |
6.06% |
|
Lymphoma |
1 |
1.51% |
|
Anaplastic carcinoma |
1 |
1.51% |
|
Total |
66 |
100% |
Findings of the present study revealed low
papillary to follicular carcinoma ratio
and relative higher incidence of follicular carcinoma. Various studies
like Ezaki Haruo et al 1992(papillary-78.4%, follicular - 17.2%, papillary
to follicular ratio 4.6)(3), Segovia Gomez et al (Papillary –76%,
follicular –18%, papillary to follicular ratio –4.2)(4), Harach et
al (papillary to follicular ratio-6.2)(5) revealed relative lower
follicular carcinoma and higher papillary to follicular carcinoma ratio.
Williams et al
(6) found a relatively higher frequency of follicular carcinoma in Cali and Manddoza goiter endemic
areas, with papillary to follicular carcinoma ratio being 1.3:1, and 0.9:1 respectively. In
Northeast Scotland and Iceland (iodine rich areas) the ratio is 3.6:1 and 6.5:1
respectively.(6)
The histological pattern of malignant thyroid tumors in our study in Goa is following
the histological pattern of iodine deficient places. Goa is a coastal area and
people consume seafood rich in iodine. But a survey conducted by National Goitre
Control Survey Team (NGST) in Goa reported total goiter rate (TGR) of 34.9% in1993.(7) A study by Kapil et al conducted in Tiswadi block
of Goa found total goiter rate of 16.6%.(8) The median urinary iodine was 5.5
mcg per 100 ml indicating moderate iodine deficiency amongst the population
studied.(8) They also surveyed salt sample and found that 48.9% of salt sample
did not have any iodine.(8,9) A possibility of goitrogens present in food of
coastal places like Panaji was also suggested by Kapil et al
From our own work and parallel evidence already quoted we would conclude that a
low dietary intake of iodine is associated with a low papillary to follicular carcinoma ratio. We would
also like to conclude that the histological pattern of thyroid carcinoma in Goa is
compares with the histological pattern in iodine deficient area, supporting the
findings of Kapli et al.(8) The authors want to stress that Goa needs an
urgent and detailed study of iodine deficiency disorders
and iodisation status.
Our study shows
that the ratio of papillary to follicular carcinoma in Goa conforms to a iodine
deficient status. Further investigations are needed to assess
the overall iodine status of population in Goa and need for urgent iodine prophylaxis.
-
Chan KC, John. Tumors of thyroid and parathyroid gland. In
Fletcher CDM Editor. Diagnostic
histopathology of tumors. 2nd edition. London: Churchill
Livingstone.
2000.
-
Rasmussen-Ulla Feldt. Iodine and
cancer. Thyroid 2001:11;483-486.
-
Ezaki Haruo, Ebihara Satoshi et al.
Analysis of thyroid carcinoma based on material registered in Japan during
1977-1986 with special reference to predominance of papillary type. Cancer
1992:70; 808-814.
-
Segovia Gomez I, Gallowitsch HJ et
al. Descriptive epidemiology of thyroid carcinoma in Carrinthia, Austria:
1984-2001. Histopathologic features and tumor classification of 734 cases under
elevated general iodination of table salt since 1990: Population based age
stratified analysis on thyroid carcinoma incidence. Thyroid 2004:4;277-286.
-
Harach HR, Williams ED. Glandular
(tubular and follicular) variants of medullary carcinoma of the thyroid.
Histopathology 1983:7;83-97.
-
Williams et al. Thyroid cancer in an
iodine rich area. A histopathological study. Cancer 1977;39:215-222.
-
The National Goitre control programme. A blue print for its Intensification. Nutrition foundation of India
scientific report. New delhi 1983 pp36-38
-
Kapil et al. Assessment of iodine
deficiency in Tiswadi block, Goa Indian practitioner vol XLIX no 9, 749-750.
-
Kapil U. Current status of iodine
deficiency disorders. Indian Pediatr 1998;35:831-836
|
