This study has used a comprehensive approach in assessing the factors that underlie the social and clinical pathway to cancer diagnosis duration in CRC. Findings show, as in the review of Mitchell et al. , the complex relationship between symptom presentation and patient behaviour regarding perception and response to the symptoms. Moreover, our results add more information on the effect in time elapsed from symptom to diagnosis or treatment of factors such as gender, attitude towards symptoms, appropriate GP referral and hospital doctor performance.
First of all, after experiencing the first CRC symptoms, half of the patients have to wait at least 4 months until diagnosis. This finding is similar to that described by others [20–24]. Most notable is the fact that one third has to wait more than six months to be diagnosed. In accordance with other findings [20, 25], no differences in distinct symptom duration intervals by cancer site were detected, although some studies reported longer time for rectum [26, 27].
Women in our study are more likely to experience longer time to diagnosis than men. These results probably are related to gender differences in coping with symptoms and help-seeking behaviour [10, 28–30]. Women push men to see a doctor when they have CRC symptoms while the women themselves wait for symptoms to clear up  because of fear of having cancer . In fact, waiting for symptom clear-up was associated in our study with not being diagnosed or treated promptly.
There are no conclusive results on socioeconomic status and time elapsed to diagnosis and treatment. Some studies show longer symptom duration in those patients with lower social status [22, 28, 32, 33] while our data, in accordance with others [34, 35], could not confirm these differences. Longer lag time is also seen in those patients with history of cancer in family members, friends or colleagues. These factors have not been researched in depth with regard to CRC and delay . While Ratcliffe et al. describe no differences in time intervals in those with or without family history of cancer , other authors have suggested that prior experience of the disease through relatives or friends could result in putting medical consultation off [10, 37].
Regarding symptom at presentation, we confirmed that abdominal pain [38–40] and vomiting [32, 39] lead to shorter interval duration. At the same time, as described by other authors [28, 40], our results show that beliefs that the symptom is serious and symptom disclosure to friends and family are strongly associated with shorter lag times. Again, this could be related to gender, as women with CRC symptoms generally say nothing to their families until they have already visited a doctor .
Current practice by general practitioners may contribute to lengthen time to diagnosis. For instance, we observed that when the GP requests some tests to diagnose anemia, the diagnosis process is extended . Unfortunately, there is no simple solution to this. When dealing with a symptom such as anemia, with low predictive value, doctors must confirm non-malignancy before filling outpatient services with mild pathologies [13, 14]. Similarly, misinterpretation of a symptom may result in a greater number of visits to a doctor before referral to a specialist [32–34, 39–43], and this is a variable associated in our study with longer time to diagnosis or treatment.
Furthermore, erroneous orientation can be the result of poor examination and misdiagnosis. Our results show that the GP only carried out physical examination of one in three patients; in fact, prior studies have pointed out insufficient physical examination by the GP, and no improvement has been observed over time [40–42]. Lack of physical examination and poor investigations by outpatient or emergency doctors seem to have more consequences than family doctor performance . This could be partly due to the fact that a misdiagnosis in a primary care visit is less important because continuity of care is highly assured. A misdiagnosis in outpatient care would be more relevant because a further appointment is considerably more difficult to make.
On the other hand, the capacity of the GP to form a suspicion of CRC in the referral has been shown to be a key factor as it predicts less time to diagnosis. This may be because when the GP has a clear suspicion, the referral is made more promptly and the response of hospital doctors to this type of referral is faster [44, 45].
Strengths and limitations
In contrast with previous studies limited to the assessment of partial time intervals to diagnosis or treatment (patient or system time intervals), we have been able to show that these factors also affect total time to diagnosis or treatment. Our findings show a similar relationship for time to diagnosis and time to treatment with the various factors studied. This fact demonstrates that the variables considered in this study have great influence on the time to diagnosis and, as a matter of fact, duration between diagnosis and treatment is relatively less relevant (>65% of those diagnosed are treated within a month). The inclusion of a high number of hospitals and primary care centers could imply high heterogeneity in data acquisition, but at the same time represents a complete picture of patterns of care, preventing the selection bias that appears when only a single centre is included.
The major limitation of this study lies in the lack of a consistent methodology to precisely measure the date of symptom presentation. The date of onset of symptoms obtained from the patient interview has been questioned. According to some authors, studies fail to consider existing theories of symptom interpretation. The interpretation of bodily sensations as symptoms is embedded within a social and cultural context and respondents do not define time periods in the same way . Therefore, this date may be quite precise for acute symptoms, such as rectal bleeding, but difficult to establish for more general symptoms such as fatigue . However, other studies have shown good agreement when comparing information expressed by patients and doctors [18, 48]. Retrospective review of clinical records presents the same type of problem because it comes from patient information provided to doctors. Furthermore, some of the symptoms described to doctors may go unrecorded, as highlighted by some authors [49, 50]. Patient interviews conducted during pre or post first treatment could result in memory biases. The Aarhus statement will facilitate standardized and uniform definition of studies in this area . Finally, a trusting relationship with the GP, recorded after diagnosis, could be spurious as, patient faith in their GP, could be related to lag time to diagnosis or treatment [52, 53].