It is not possible to reach clear conclusions on the association between cancer outcomes and time intervals to diagnosis and treatment due to heterogeneity across the evidence base, both in terms of time intervals examined and the outcomes that are measured. Studies are mainly retrospective and at high risk of confounding by indication, for example where patients with severe symptoms are diagnosed and treated very quickly but have poor outcomes due to aggressive disease.
Well conducted systematic reviews were identified for the following cancer types:
- head and neck cancers - two systematic reviews reported that longer intervals to diagnosis and from diagnosis to treatment were associated with poorer survival outcomes. A referent interval of 30 days was commonly used in studies.
- colon cancer - four out of five studies included in a systematic review reported no association between longer intervals from diagnosis to initiating surgical treatment and overall survival outcomes. Interval categories analysed ranged from >31 days to >60 days.
- prostate cancer - most studies identified in a systematic review did not find an association between longer time to treatment (variously defined) and oncologic outcomes, such as biochemical recurrence and cancer stage. None found a relationship with metastases or reduced survival. The majority of studies only included low risk patients.
Systematic reviews on bladder cancer and non-small cell lung cancer are in preparation for publication.
Peer reviewers and collaborators in the development of this Evidence Synthesis highlighted that the patient interval - from initial awareness of symptoms to first presentation/clinical appearance – may be an important contributor to cancer outcomes.
What were we asked to look at?
To inform an ongoing clinical review of cancer waiting times in Scotland we were asked to summarise the published evidence on the association between time intervals to diagnosis and treatment and cancer outcomes.
Why is this important?
It is important to understand the likely impact of variations in cancer waiting times across various cancer types to help ensure optimal outcomes for patients and inform planning and policy for cancer services in Scotland.
Scottish Government Cancer Waiting Times Review Implementation Group