American Journal of Epidemiology Advance Access originally published online on November 28, 2006
American Journal of Epidemiology 2007 165(4):473; doi:10.1093/aje/kwk097
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
LETTERS TO THE EDITOR |
RE: "RISK OF SECOND PRIMARY MALIGNANCIES IN WOMEN WITH PAPILLARY THYROID CANCER"
1 Department of Nuclear Medicine, 417 NIMTS Army Veterans Hospital, Athens 11528, Greece
2 Department of Nuclear Medicine, University Hospital of Ioannina, Ioannina 45110, Greece
(e-mail: csioka{at}yahoo.com)
We read with great interest the article by Canchola et al. (1) concerning the occurrence of second primary cancers after diagnosis of thyroid cancer in women with papillary thyroid cancer. The authors presented follow-up data on 10,932 female thyroid cancer patients. Among them, 279 (2.6 percent) developed a second primary cancer during 50,938 person-years of follow-up (mean = 4.7 years) (1). The results of this study showed an increased risk of in situ breast cancer, kidney cancer, and melanoma. The authors recommended increased awareness of this cancer association for early diagnosis and management of the second malignancies. Similar analyses were performed for colon, lung, endometrial, and ovarian cancer, but no association was found, although the number of cases observed in some subgroups was small.
However, the study by Canchola et al. (1) did not address the reciprocal risk of thyroid cancer after the first diagnosis of either breast cancer in situ, kidney cancer, or melanoma. Interestingly, we have investigated the occurrence of second malignancies in female patients with differentiated thyroid cancer either before the appearance of the thyroid cancer or later, and we would like to share our findings. Specifically, we followed 120 female patients with differentiated thyroid cancer who were treated with surgery followed by 3.7 MBq (100 mCi) of iodine-131 at our institutions from 1996 to 2002. The appearance of other primary cancers before or after the diagnosis of thyroid cancer was studied for a period of 3–9 years.
Overall, seven of 120 (5.8 percent) patients had second malignancies. The diagnosis of a second malignancy predated thyroid cancer diagnosis in four patients (3.3 percent) and followed thyroid cancer diagnosis in three patients (2.5 percent). The preexisting malignancies consisted of a colorectal cancer diagnosed in one woman 1 year prior to thyroid carcinoma, an undifferentiated mediastinal tumor diagnosed in one woman 26 years prior to thyroid carcinoma, and two breast carcinomas diagnosed in two women 1 and 14 years prior to thyroid carcinoma. The metachronous malignancies consisted of one colorectal cancer diagnosed in a woman 1 year after thyroid cancer and two breast cancers diagnosed in two women 1 and 7 years after thyroid cancer.
Our findings are in accordance with the results observed by Canchola et al. (1), though in a much smaller number of patients. However, the appearance of some malignancies prior to thyroid cancer diagnosis suggests that the association of thyroid cancer with other tumors may not represent a treatment effect but rather may be due to common risk factors. In a previous study that pooled data from 13 cancer registries, Sandeep et al. (2) found a 30 percent increased risk of second primary cancers after thyroid cancer. They also found an increased risk of thyroid cancer after the occurrence of a variety of these cancers, suggesting possible shared risk factors and treatment effects in the development of these cancers (2). In another study carried out in a European cohort of 6,841 thyroid cancer patients, Rubino et al. (3) found 576 patients with second primary malignancies, demonstrating an increased risk of 27 percent. Similarly, after studying 49,207 breast cancer patients and 4,911 thyroid cancer patients, Sadetzki et al. (4) suggested possible early exposure to common risk factors or genetic susceptibility for both malignancies. Thus, the excess incidence of breast carcinoma after thyroid carcinoma may not be related to radiation treatment (5).
In summary, it appears that there is a relation between thyroid cancer and a variety of other malignancies. Future studies should focus on genetic predisposition, specific gene alterations, and/or common risk factors for the development of these tumors.
 |
ACKNOWLEDGMENTS |
|---|
Conflict of interest: none declared.
|
References |
|---|
 TOP References |
|---|
- Canchola AJ, Horn-Ross PL, Purdie DM. (2006) Risk of second primary malignancies in women with papillary thyroid cancer. Am J Epidemiol 163:521–7.
[Abstract/Free Full Text] - Sandeep TC, Strachan MW, Reynolds RM, et al. (2006) Second primary cancers in thyroid cancer patients: a multi-national record linkage study. J Clin Endocrinol Metab 91:1819–25.
[Abstract/Free Full Text] - Rubino C, de Vathaire F, Dottorini ME, et al. (2003) Second primary malignancies in thyroid cancer patients. Br J Cancer 89:1638–44.[CrossRef][Web of Science][Medline]
- Sadetzki S, Calderon-Margalit R, Peretz C, et al. (2003) Second primary breast and thyroid cancers (Israel). Cancer Causes Control 14:367–75.[CrossRef][Web of Science][Medline]
- Adjadj E, Rubino C, Shamsaldim A, et al. (2003) The risk of multiple primary breast and thyroid carcinomas. Cancer 98:1309–17.[CrossRef][Web of Science][Medline]
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  P. L. Horn-Ross and A. J. Canchola TWO OF THE AUTHORS REPLY Am. J. Epidemiol., February 15, 2007; 165(4): 474 - 474. [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||