Measures of promptness of cancer diagnosis in primary care: secondary analysis of national audit data on patients with 18 common and rarer cancers

Background: Evidence is needed about the promptness of cancer diagnosis and associations between its measures. Methods: We analysed data from the National Audit of Cancer Diagnosis in Primary Care 2009-10 exploring the association between the interval from first symptomatic presentation to specialist referral (the primary care interval, or 'interval' hereafter) and the number of pre-referral consultations. Results: Among 13 035 patients with any of 18 different cancers, most (82%) were referred after 1 (58%) or 2 (25%) consultations (median intervals 0 and 15 days, respectively) while 9%, 4% and 5% patients required 3, 4 or 5+ consultations (median intervals 34, 47 and 97 days, respectively) (Spearman's r=0.70). The association was at least moderate for any cancer (Spearman's r range: 0.55 (prostate) -0.77 (brain)). Patients with cancers with a higher proportion of three or more pre-referral consultations typically also had longer median intervals (e.g., multiple myeloma) and vice versa (e.g., breast cancer). Conclusion: The number of pre-referral consultations has construct validity as a measure of the primary care interval. Developing interventions to reduce the number of pre-referral consultations can help improve the timeliness of cancer diagnosis, and constitutes a priority for early diagnosis initiatives and research.