Management of Differentiated Thyroid Carcinoma

Management of Differentiated Thyroid Carcinoma



I Initial Assessment of the Thyroid Nodule (indicating risk of malignancy)

Size more than 1 cm
Recent increase in size
Associated symptoms: dysphagia, hoarseness of voice, local pain, stredor, dyspnoea, systemic symptoms suggestive of metastatic disease.
Age less than ten or more than 60 yrs
Male sex
Family history of thyroid cancer, breast cancer or previous hysterectomy
History of radiation

II Fine-Needle Aspiration Cytology (FNAC)

To be done in all cases
* Ultrasound may be considered in areas endemic for goiter FNAC is to be done by a trained cytopathologist or endocrinologist/surgeon with a cytologist for assistance
Site of FNAC – it is to be done from a solitary/dominant nodule of a multinodular goiter/solid part of a mixed lesion (ultrasound guidance)

III Management Based on FNAC findings

Benign: follow up six monthly, reassure
Inconclusive: treat according to risk category/if clear fluid aspirated, treat as benign
Hemorrhagic -exclude malignancy

If, Malignant or Suspicious, operate based on the following protocol

(a) When diagnosis is confirmed preoperatively When well differentiated Ca thyroid is confirmed in a patient preoperatively near total thyroidectomy is recommended.

(b) When diagnosis is not confirmed preoperatively i.e. FNAC is suspicious – When preoperatively diagnosis is not confirmed or is doubtful, frozen section biopsy (if available) – may be used to help surgeons.

The decision to undertake total/near total thyroidectomy may be made also by the clinical judgement of the surgeon based on the intraoperative findings.

(c) This pertains to the histological surprise of malignancy after thyroidectomy (Here the diagnosis was not entertained preoperatively but after thyroidectomy the pathologist reports well – differentiated carcinoma) – After hemithyroidectomy (lobectomy + isthmusectomy) if there is a histological surprise of malignancy, in this situation re-exploration and complete total thyroidectomy is recommended. This is also done in following situations

(i) In follicular carcinoma

(ii) In high risk papillary carcinoma thyroid by anyone of the risk stratification classification.

In low risk group and in cases of papillary carcinoma less than 1 cm, the decision to re-explore and complete thyroidectomy should be decided by the surgeon and the patient after complete discussion.

(d) Pertains to histological surprise of malignancy after subtotal thyroidectomy In the event of histological surprise of malignancy after subtotal thyroidectomy.

(i) Patient can be followed up when complete lobectomy of the more affected side and subtotal lobectomy on the opposite side has been done.

(ii) When bilateral subtotal lobectomy has been done, the decision to reoperate or to ablate the remnant can be decided by discussion between the surgeon, endocrinologist and nuclear medicine specialist.

IV. Postoperative Follow – up

Ablation therapy at four to six weeks: Completion thyroidectomy as mentioned before, is required if the surgery is found to be inadequate; however, in inoperable cases, or when patients refuse surgery, I-131 ablation is to be done by the nuclear medicine specialist after discussion with the endocrinologist and the surgeon. A post therapy delayed whole body I-131 scintigraphy is essential to look for the presence of distant functioning thyroid metastases.

Dosage of I-131

In centres where quantitative dosimetry is not possible the consensus arrived was to have empirical dosage of I-131 as follows
Thyroid remnant ablatin – 40 to 60 mCi
Nodal metastases – 100 to 150 mCi
Pulmonary metastases – 150 to 180 mCi
Skeletal metastases – 250 to 300 mCi

All such patients need isolation for varying periods of 2-5 days depending on the dosage of I-131 administered and their daily exposure rate readings.

V. Thyroxine Suppression

All patients after completion thyroidectomy and residual I-131 ablation should be put on thyroxine suppressive therapy. The usual thyroxine dose is 2.5 mg/kg/day, and the dose is adjusted to keep TSH below 0.1 mIU/ml.

VI. Further Follow-up

Follow up total body scan, at six months and yearly thereafter, till three consecutive negative scans are recorded.

I-131 whole body scans are to be done when the patient has stopped thyroxine for four-six weeks or when S.TSH is more than 30 uIU/ml.

Serum Thyroglobulin levels to be done even every six months, in these cases, where total thyroid ablation was achieved and can be used as a good marker for follow up, especially when I-131 scan is not feasible.

The team of treating endocrinologist, physician and surgeon can decide on the frequency of further follow-ups. These patients are to be educated on the need of long-term follow ups.

All the patients must be on life long suppressive therapy with thyroxine. The dose of thyroxine are adjusted on the basis of serum TSH level, which is to be monitored every six months.