Managing differentiated thyroid cancer
Authors: P. Kendall-Taylor
Journal: BMJ (2002)

Although differentiated thyroid cancers are not common, they are as common as cervical cancer and multiple myeloma and are the commonest malignant endocrine tumours. Furthermore, they are among the few curable cancers. When managed according to best practice the vast majority of patients can expect cure, so good management is mandatory. Five year survival rates for adults with thyroid cancer in England (64% for men, 75% for women) are below the European average (72% for men, 80% for women).1 This reflects the general position that patients with cancer in the United Kingdom suffer more delays and have worse survival than in many other European states.2 The British Thyroid Association has recently produced guidelines on managing differentiated (papillary and follicular) thyroid cancer and medullary thyroid cancer.3 The aim of the guidelines is to improve long term overall and disease free survival, enhance patients' health related quality of life, and improve referral pattern and management of patients with thyroid cancer.

The annual reported incidence of thyroid cancer in Britain is 2.3 per 100 000 women and 0.9 per 100 000 men (data from the Scottish Cancer Registry). In England and Wales about 900 new cases and 220 deaths are recorded every year.4 The 10 year survival rates for papillary and follicular thyroid cancer in large American series were 93-94% and 84-85% respectively.5,6 Local or regional recurrences develop in up to 30% of patients and distant metastases in up to 20%.7,8 The recurrence rate increases with time, and 40 year recurrence rates are about 35%.8 Overall 8-10% of patients with a diagnosis of thyroid cancer die of their disease.6,7

Patients at high risk of recurrence and death from thyroid cancer can be identified at the time of diagnosis by considering well established prognostic factors. The principal indicators of poor prognosis are extremes of age, male sex, tumours with poorly differentiated histological features, and advanced tumour stage. Treatment also clearly influences prognosis. In particular, adequate surgical treatment and the use of iodine-131 ablation therapy have been shown to produce reduced recurrence rates and lower disease specific mortality.6 Large retrospective studies have suggested a tendency for improved outcomes over the past few years. This is thought to be a consequence of the increasing use of total thyroidectomy and 131I ablation, as well as other factors such as the use of serum thyroglobulin to monitor for recurrence and more effective suppression of thyroid stimulating hormone levels by thyroxine. Not only has detailed analysis of the data shown powerfully the important effect of meticulous initial treatment on prognosis,8 it has also documented the effects of delays in diagnosis and treatment on mortality.6

Although the reasons for the poor outcome in the United Kingdom may be multifactorial, thyroid cancer is clearly not managed well in Britain. Several groups have audited their management of thyroid cancer and have identified deficiencies in practice. For example, in one centre 12-20% of cases were inadequately managed with respect to adequacy of surgery, adequacy of thyroid stimulating hormone suppression, monitoring by serum thyroglobulin, and use of 131I therapy.9 Such identifiable deficiencies emphasise the need for locally agreed protocols and for centralisation of expertise and patient management.

The British Thyroid Association guidelines aim to support such protocols. The guidelines were developed through the collaboration of specialists from all relevant disciplines and patients. They are based on a systematic review of the literature, and recommendations are graded according to the strength of the evidence.3 They include key recommendations and a section for primary care physicians and are accompanied by three patient information booklets.10 The recommendations accord with the latest requirements in the NHS Manual of Cancer Services Standards.11

One important recommendation of the guidelines is that patients with thyroid cancer should be managed by regionally designated multidisciplinary teams. Patients will normally be referred to a member of the team and the treatment plan discussed by the whole team, preferably in a combined clinic. Each of the specialist members of the team (surgeon, endocrinologist, pathologist, oncologist) should have been trained in and have expertise in managing thyroid cancer.

Several evidence based reviews of management of thyroid cancer are available7,8 which discuss various controversial aspects of treatment. The balance of evidence favours an approach in which most patients with differentiated thyroid cancer will have fine needle aspiration cytology for diagnosis and treatment planning. Those with tumours more than 1 cm diameter will generally undergo total or near total thyroidectomy with central node dissection, usually followed by 131I therapy and thyroid stimulating hormone suppression. Serum thyroglobulin is used to monitor for recurrence, with isotope scans when indicated. External beam radiotherapy is rarely required. Recombinant human thyroid stimulating hormone is now available and has an evolving role in managing selected cases.12 Follow up should be lifelong because thyroid cancer has a long natural history: late recurrences do occur and can be successfully treated.

The intention is that the guidelines should be adopted by regional cancer networks and that they should be an essential reference for all involved in treating patients with thyroid cancer, whether managers, hospital doctors, specialist nurses, primary care physicians, or professional organisations. We hope that implementation of the guidelines through local protocols will lead to the delivery of high quality care across the United Kingdom and improved survival for patients with thyroid cancer.