Comparison of existing literature
The potential negative side effects (physical and psychological) and costs of cancer surveillance strategies have not been well delineated [4–7]. None of the studies included in the previous reviews of colorectal cancer surveillance have provided any specific details of the harms (mortality or morbidity) resulting from investigating or treating recurrences [2, 3]. However, a potential harm from any secondary prevention program is well recognised to be over-diagnosis and false positive tests [7, 11].
Some researchers have investigated the psychological effects of colorectal cancer surveillance [8, 12, 13]. None of these studies have found deterioration in the patient QoL with surveillance. Nevertheless, in recent meta-analyses, it was shown that anxiety, rather than depression, was a major problem among long-term cancer survivors. It is unknown, however, what impact a cancer surveillance program itself has on anxiety levels .
The challenge of postoperative cancer surveillance is that a vast majority of patients must undergo a large number of tests without any benefit, or even with some potential harm, to identify a few patients with curable recurrence. The high rate of false positive tests (n = 34, 30% of all surveillance patients) in this trial was more than we expected and likely negatively impacts the patient’s and family’s QoL. False positive and true positive tests in colorectal cancer surveillance have been addressed in previous reviews . According to Kievit et al., 370 positive surveillance tests (26 true positives, 7%) and 11 surgeries were required to provide one patient with a long-term survival benefit (five years) . In our survey, 1186 tests were performed during the 1884 person-month surveillance period, which equals 276 tests per successful R0 metastasis surgery. This finding aligned with the results from another Norwegian survey, which reported 270 tests per successful R0 resection . The estimated cost of £ 103207 per successful R0 metastases resection is higher than reported by other authors. Kørner et al. reported an estimated cost per R0 resection of £ 15278 (US $ 25289),
Identification of asymptomatic but incurable recurrent disease through surveillance testing raises ethical and quality of life considerations [5, 17]. In our study, three patients (21%, Table 4) had asymptomatic but incurable colon cancer recurrence. These figures are somewhat higher than those in a previous study reporting 9% asymptomatic but incurable disease detected in a surveillance program .
The imperfect nature of specific surveillance tests themselves (i.e., test sensitivity and specificity) can contribute to the potential harms of surveillance. National surveillance programs are often based on serial CEA measurements, and this biomarker has several pitfalls and shortcomings. A recent study showed that the diagnostic accuracy of serial CEA measurements is low and is impacted by the cut-off value used . Similarly, radiological tests have varying sensitivity and specificity, the latter of which impacts the rate of false positive tests. For example, the rate of false positive tests in CT chest scans has been reported to be as high as 30-50%; as a result, this test is not recommended by some physicians for post-treatment surveillance purposes .
Studies of secondary prevention practices around other cancer types have explored potential harmful effects of these programs. In a systematic review addressing screening for lung cancer using thoracic CT scans, most of the detected lung nodules (> 90%) were benign, and invasive nonsurgical procedures in patients with benign lesions were common . Forty-six percent of patients reported psychological distress while awaiting the confirmation of a potential cancer diagnosis . Thus, the potential harms of a preventive program must be carefully weighed against any benefits [20–22]. In the case of colonoscopic colorectal cancer surveillance, the potential harms of the procedure (including significant discomfort, bleeding, and perforation) coupled with the low rate of intraluminal cancer recurrence, have led some to debate whether colonoscopy should be routinely included in surveillance programs .