Delays in cancer diagnosis: Which are the hardest tumours to diagnose early
One of the big challenges in cancer care is the early diagnosis of disease; early diagnosis is critical if we want to cure patients of cancer, but some tumours give rise to non-specific symptoms and therefore might not be identified by GPs at the early stages. It has long been known that some tumours are detected at earlier stages than others, and this has important implications if we want to focus on early detection strategies. Some types of cancer would not benefit from these schemes, whereas others would. Lyratzopoulos et al. , writing in Lancet Oncology, used the number of GP visits before diagnosis as a surrogate for the delay until diagnosis.
The authors used information from the 2010 National Cancer Patient Experience Survey in England, specifically the section asking about the number of GP visits for their symptoms before their cancer diagnosis. Using a multivariate logistic regression model (accounting for age, gender, deprivation status and ethnic group), they calculated the odds ratio of visiting a GP three times or more for each cancer site, compared to a reference of one for rectal cancer.
They found that females, younger patients, non-white patients and the most deprived groups were significantly more likely to visit a GP three times or more compared to males, older patients, white patients and the most affluent groups (hence why these were adjusted for in the multivariate logistic regression model).
Using their model, they identified the cancers with the highest odds ratios of visiting a GP three times (i.e. the “hardest” to diagnose) as multiple myeloma (OR 3.42 compared to rectal cancer), pancreatic (OR 2.35), stomach (OR 1.96) and lung (OR 1.68). The cancers with the lowest odds ratios (i.e. the “easiest” to diagnose) were breast (OR 0.19 compared to rectal cancer), melanoma (OR 0.34), testicular (OR 0.47) and endometrial (OR 0.59). However, looking at the odds ratios for certain cancer types in different subgroups also showed interesting trends; for example, for bladder cancer women were much more likely than men (OR 2.31) to have seen a GP three times, suggesting that bladder cancer is diagnosed much earlier in men than women.
Although there are some limitations to this study (it was based on a patient questionnaire with potential for inaccurate recall, it did not specify what time period the pre-diagnosis visits were within, and importantly only surveyed cancer survivors, and so cannot give information about the number of visits of patients who died), it does give some interesting results and suggests that early diagnosis strategies should be focused on certain tumours (e.g. multiple myeloma, pancreatic). It also suggests that there should be a focus on identification of tumours in certain subgroups in whom symptoms may be overlooked or put down to other causes; for example, GPs may attribute lower urinary tract symptoms in women to infection where they would be more worried about tumours in men. This paper is very informative and provides an evidence basis for future interventions to improve early diagnosis.
1. Lyratzopoulos G, Neal RD, Barbiere JM, Rubin GP, Abel GA. Variation in number of general practitioner consultations before hospital referral for cancer: findings from the 2010 National Cancer Patient Experience Survey in England. Lancet Oncology 2012 Apr; 13(4): 353-365.
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