Higher adherence rates to surveillance recommendations in CRC have been associated with better cancer-mortality18. In addition, patient surveillance improves the care of those patients who could potentially benefit from curative treatments2.
In this cohort, the overall adherence to surveillance recommendations for CRC survivors was slightly superior to 50%, a number that we considered high compared to other populations10,11. However, 46.2% of patients did not comply with adequate surveillance according to Cooper’s definition, and 59.3% of patients did not comply with our proposed modified composite definition, which includes the CT scan. When comparing our overall adherence against other populations, compliance to the guidelines on post-treatment surveillance is higher than the reported at similar centers in other world regions Kupfer et al11 reported an overall adherence of 22.8% at three NCI-designated cancer centers, and Cooper et al12 reported an overall adherence of 17% in Medicare beneficiaries.
The surveillance component with the highest adherence in other populations was the medical visit, with an overall adherence between 70–92%10. Similarly, the component with the lowest adherence in other populations was colonoscopies, with an adherence between 18–61%10. Our results show that colonoscopy was the individual component with the highest adherence rate, even though it is an invasive procedure. This might be because it only requires completing one examination in the three-year surveillance period. Additionally, medical visits had consistently high compliance throughout the three-year period. The medical visit represents the minimum component that some guidelines suggest for follow-up, which is relevant in resource-limited contexts, like many regions in Mexico.19 The individual component with the lowest adherence rate was the CT scan. The lack of adherence to CT scans could be due to oncologists’ preferences based on patients’ characteristics and changing evidence. During our study period (2014–2016), a randomized clinical trial conducted by Primrose et al6 in the UK revealed that surveillance with CEA and CT measurements increased the chance of receiving a curative resection. However, when they compared the intensive and the minimal follow-up groups, there was no significant impact on survival (overall survival of 18.2% vs. 15.9%, p = NS). This study could have impacted the request for CT scans in our institution. More recently, results of the COLOFOL Randomized Clinical Trial 3 did not show a significant difference in five-year mortality between those patients who received high-intensity surveillance (CEA and CT scan at 6, 12, 18, 24, 36 months) and those who received low-intensity surveillance (CEA and CT at 12 and 36 months) (13 vs. 14.1%, p = 0.43) 8. Even with this evidence, CT is still part of surveillance recommendations in guidelines, and our work shows it might have a relevant role in detecting recurrences without enough evidence about its impact on survival in this cohort.
Previous studies in other populations have found that some factors may impact adherence to surveillance recommendations10,11. In our study, we did not find statistically significant predictors of adherence to follow-up recommendations, which might be explained by our small sample size. Nevertheless, we recognize that circumstances related to the patient, physician, and the health system influence the adequate surveillance of CRC survivors. Patient education and shared decision-making to offer the best possible care are effective strategies to improve adherence. Several CRC screening studies have found that narrative communication strategies like sharing stories or testimonials positively influence adherence, mainly due to greater emotional engagement20,21,22. This approach could be implemented using videos, images, or leaflets of patients who have had a positive experience following surveillance regularly21,22. Other suggestions include reminders for appointments generated by the electronic medical records23,24; the inclusion of a medical team member who aids patients in arranging upcoming medical visits and organizing them, and avoiding confusion in the appointments ordered by the medical provider25. Telemedicine could also increase access to surveillance, decentralize care, and reduce patient travel costs. During the COVID-19 pandemic, we implemented a telemedicine system in our institution. This system can help patients adhere to medical visits better by avoiding traveling long distances.
Our study has several limitations. This is a retrospective study conducted in a single tertiary care center in Mexico City with a modest sample size. Therefore, it is not possible to generalize our results to other Mexican populations, as each different center has its particular follow-up system for cancer survivors. Due to the sample size, we do not have the statistical power to expose the effect of the variables analyzed on adherence. The small number of patients and the high rate of loss of follow-up could explain the higher five-year overall survival and five-year recurrence-free survival compared to other populations. Finally, factors associated with physician decisions regarding surveillance recommendations were not evaluated but could also impact adherence.
The main strength of this study is that it is the first assessment of adherence to post-treatment surveillance recommendations of CRC in Mexico. We assessed overall adherence and to individual components of surveillance in the first three years of follow-up, the period where the majority of recurrences in CRC occur (60–80%)2. This study provides valuable evidence to improve adherence by focusing on the components of surveillance where we found the lowest adherence rates and taking advantage of the components of surveillance with higher rates. As for medical visits, telemedicine can be implemented for patients from outside the metropolitan area.
In conclusion, in our institution, compliance to the guidelines on post-treatment surveillance is higher than the reported at similar centers in other world regions, though there is a decreasing trend in adherence during the study period. Nevertheless, it is difficult to generalize this knowledge to other Mexican populations as each cancer center has its own method of implementing surveillance systems. Multi-institutional studies with a bigger sample size are needed to have more certainty about our findings. More evidence will help us understand the potential barriers to surveillance in our population and implement strategies to improve compliance to surveillance and the survival of patients.