Dear Editors,

The results presented in the article by Borges et al.,¹ entitled ‘Thyroid cancer in Brazil: a descriptive study of cases informed by hospital cancer records, 2000-2016’, published in RESS volume 29, issue 4, show the potentialities of hospital cancer records (HCR) for outlining the diagnosis and treatment profiles of health service users with thyroid cancer in Brazil. At the same time they also reveal the weaknesses of this system used in Brazilian National Health System (SUS) accredited care facilities for users with cancer.

In keeping with the national and international literature,^2,3,4 the above mentioned study highlighted an increase in thyroid cancer cases in Brazil, even though 3,482 cases (6.2%) were excluded from the 56,394 potentially eligible cases due to missing information on histological type. The low percentages of incompleteness (<5%) of the ‘sex’, ‘age’, ‘previous diagnosis and treatment’ and ‘Federative Unit’ of residence and of treatment variables enabled the following to be observed: (i) the higher sex ratio; (ii) age distribution and tumor type (45-55, 50 and 60 years, for differentiated carcinoma, medullary carcinoma and anaplastic carcinoma, respectively); and (iii) migration of people seeking care as a cause of delays in their treatment.

The study reduced the high incompleteness of tumor staging to 39.6% by using the correlation between staging and TNM Classification of Malignant Tumors. Tumor staging is recognized as the variable that defines the most adequate treatment as well as prognosis; notwithstanding, the reduction method used in the study is not described sufficiently clearly to enable it to be reproduced.

It should also be noted that the methods section of the article does not describe how the information on radiotherapy with iodine was obtained, given that this treatment option is not available on the HCRs. The only available option is radiotherapy. When considering the two equivalent modalities, there is a risk of inadequate interpretations, as they are different therapies, both with regard to their indication and also with regard to their purposes, both of which are dependent on variables and specificities that differ in the three groups of tumors analyzed.

The manuscript’s authors emphasize the need for proper filling in of medical care records, since they are sources of data for planning, controlling and evaluating the care network for users with cancer. We would also add the fact that some of the limitations arise from problems with the HCRs. An example would be to point out the need to revise the Tumor Record Form, especially with regard to treatment modalities - for thyroid neoplasms, in this case - as well as the need for the TNM classification to be updated as and when it is published