Discussion
When the suspicion of cancer is raised, it is a time of stress and anxiety for patients and their families (3). The cancer waiting times targets have been introduced to support diagnosis and treatment delivery in Scotland (1). Although 10 major cancers are included in these times, currently thyroid cancer is not (1). This is despite the fact that the lifetime risk in women is similar to liver and oral cancers, both of which are included (1, 4). In addition, global incidence of DTC is increasing (5).
In contrast to most malignancies, patients diagnosed with DTC generally have an excellent prognosis, with survival exceeding 90% at 10 years (6). Despite the favourable disease biology, the level of psychological distress suffered by patients diagnosed with DTC is similar to that of malignancies with much worse prognoses (3).
Few groups have looked at waiting times in DTC cohorts. To date, no effect of treatment delay on mortality has been established. Although diagnostic status of the cohort prior to thyroidectomy in most studies is unclear, they show variation in the time to treatment following DTC diagnosis from 15.3 days (7) to 114 days (8). This is likely due to discrepancies in resource availability and differences in departmental approaches.
One centre in England, where thyroid cancer is subject to ‘two-week-wait’ outpatient review targets, recorded 100% attainment (10). Interestingly, only 7% of these two-week-wait referrals resulted in a thyroid cancer diagnosis. When combining this pattern of diagnostic yield with excellent oncological outcomes, it may be the case that the application of waiting time targets in Scotland has negative repercussions for the broader cancer population while offering little benefit for the DTC cohort.
Classical cancer pathways include: a symptomatic presentation; pre-diagnostic testing; a point of diagnosis and staging; treatment planning; treatment and follow up. Our results confirm the fact that DTC is often found incidentally (22%). In these cases, the suspicion of cancer is only raised after the initial surgery performed for a benign indication. Clearly, in this situation, cancer target times are inappropriate.
Of the 62 patients in our study who were referred with a mass which ultimately proved to be a DTC (non-incidental) only 24 were referred on the cancer pathway (39%). A similar percentage of patients were referred from primary care as ‘routine’ (27%), ‘urgent’ (34%) and ‘urgent - suspicion of cancer’ (39%). This suggests uncertainty within primary care regarding how to refer such cases, although there was a no effect of the referral priority on time to diagnosis and treatment. It is also likely that more prominent clinical signs are associated with more advanced disease. In particular, 56% of our cohort who had a pre-operative biopsy suggestive or diagnostic of malignancy had N1 disease. Such patients are likely to be triaged to treatment with more urgency given the stage of disease.
In our unit, a significant number of the non-incidental patients did not have a diagnosis or suspicious FNA at the point of first treatment (44%). For these patients, the time from diagnosis to treatment is actually negative. Again, the cancer waiting time model is not well suited to this group.
Our results highlight the impact that a pre-operative cytological diagnosis has on a patient’s pathway, with surgeons clearly prioritising such cases. This observation confirms the importance of accurate radiological and cytological assessment in overall treatment planning.
This study is limited by low numbers and the inability to identify all patients referred with a suspected thyroid mass. This prevented us from calculating the percentage of referrals which result in a cancer diagnosis.
Our study suggests that the overall cancer time model is not well suited to DTC. 64% of patients referred from primary care were either identified incidentally or following a diagnostic procedure which actually amounted to initial therapy.
Although the biology of DTC is such that the time to treatment does not appear to impact on oncological outcomes, the psychological impact is less clear. Long waiting times from referral to diagnosis introduce uncertainty, nervousness and worry for patients and their families (3). This is true both for patients who ultimately are diagnosed with malignancy but also for those who are investigated and have confirmation of benign disease. This potential distress may reduce after surgery (3).
Given the difficulty in differentiating patients with DTC from those with either benign disease, or in the setting of nodal disease, from other malignancies, it seems reasonable to recommend that those patients with rapidly enlarging thyroid nodules, metastatic nodes, those at elevated risk of malignancy (prior radiation or family history) or those with additional risk factors should be offered rapid review in secondary care. Not only does this offer the potential to make a swift diagnosis, but allows the patient access to a healthcare professional with experience in management of this condition with whom the prognosis can be discussed. The importance of appropriate referral from primary care and accurate pre-operative cytology is clear, as both factors significantly impact the time to diagnosis and treatment.