What is the risk of cancer after a negative urgent suspected cancer referral?

Problem

Over 2 million patients are referred each year on urgent two-week wait (TWW) pathways to rule-out cancer in England. The vast majority of those referred (over 90%) do not have cancer initially diagnosed. We do not know the subsequent cancer risk following negative initial referral. This is an under researched area and of clear importance given millions going through pathways. TWW may be a ‘teachable moment’ when people are responsive and receptive to health information.

Approach

We extracted cancer registration data for all TWW referrals in England 2013/14 with five-year follow up. Eight main TWW referral groups were included. Those who had no cancer diagnosis within 12 months of TWW referral were included. Number of cancers for years 1-5 (Y1-5) was calculated, and subgroups for main TWW pathways. Expected cancer incidence for each group based on age/sex distribution was modelled. Y1-5 standardised incidence ratio (SIR) was calculated for each group following negative TWW. Analysis was for risk of all cancers and then for the same cancer type as initial referral.

Findings

There were 1.32 million TWW referrals across eight main cancer pathways in 2013/14 of which 1.13 million were found not to have cancer. Of these, 63,112 (5.4%) were diagnosed with cancer Y1-5 years post referral. Expected cancer risk in Y1-5 was 4%, SIR 1.27, i.e. 27% high cancer risk. Highest risk was in Y1-2 (SIR 1.33), with similar pattern for main referral types. The lowest absolute risk for any cancer Y1-5 followed negative breast TWW (3%), the highest was for urological and lung TWW, (8% and 7% respectively). For same cancer diagnoses as the initial TWW pathway, the lowest Y1-5 absolute risk was lower GI (0.7%, SIR 0.94). Urological and lung pathways had the highest absolute risk for the same cancer diagnoses as the initial pathway (4% and 3%, SIR 2.37 and 3.0 respectively).

Consequences

Five-year cancer risk and SIR has been calculated for the first time following negative initial TWW to compare future cancer risk across TWW pathways. Risk of any cancer was 27% higher than expected, particularly highest in the first few years, informing potential cancer reduction messaging and safety netting. Y1-5 risk was highest for those with negative initial urological and lung TWW assessments, suggesting the potential requirement for more active monitoring and follow up for this group. Following a negative lower GI TWW patients can be reassured that their Y1-5 risk of developing lower GI cancer appears lower than expected.