Limited effect of summer warming on the sensitivity of colorectal cancer screening: Table 1

Abstract

In their recent paper, Grazzini and colleagues 1 reported a decrease in the positivity of the immunochemical faecal occult blood test (iFOBT) for colorectal cancer screening during the summer period. Their results predict a higher rate of false-negative iFOBT results during the hot season. This effect is likely to be higher for patients with minor neoplastic lesions, where the haemoglobin concentration in faeces is usually lower 2 than in patients with larger adenomas or invasive cancers.Evaluating the seasonal proportional incidence of interval cancers (ICs) and hence the sensitivity of iFOBT-based screening programmes may help to clarify this point.We are soon going to publish the sensitivity estimates of five Italian iFOBT-based screening programmes according to the proportional method. 3 Now, in order to evaluate the seasonal variability of sensitivity, we have collected information about the date of the last negative screening test before the diagnosis of IC and estimated the season-specific sensitivity. The ICs that were diagnosed after a positive iFOBT followed by a negative assessment or a refusal of colonoscopy were excluded. Table 1 shows the positivity rates, the proportional incidence and the sensitivity in the summer versus the other seasons of the year.We observed a significant reduction in the positivity rates in the summer compared with the other seasons (4.53% vs 4.97%, with p<0.0001) as well as a lower sensitivity (although not at a significant level). In particular, summer showed the highest proportional incidence during the first interval-year after the screening episode (18.6% vs 12.9% in the other seasons taken altogether).It is also remarkable that winter scored both the highest positivity and sensitivity.It should be recognised that the sensitivity observed in the summer is still very good, when compared, for instance, with the standard for the sensitivity of breast cancer screening (proportional incidence <30% in the first interval-year and <50% in the second). 4 In our experience, iFOBT is still a highly satisfactory test for the first level of colorectal cancer screening, notwithstanding the reduced performance in the summer.

Accuracy of a fecal immunochemical test according to outside temperature and travel time

“…Sensitivities and specificities were examined at five different FIT cutoffs using the same FIT and the same buffer solution. Actual temperatures for each day from sampling until the beginning of the cold chain were used rather than monthly 9 , 10 or seasonal 6 averages. Our study is, to our knowledge, the first to investigate the potential influence of both temperature and sample return time on sensitivity and specificity of FIT for several cutoffs.…”

Incidence of interval cancers in faecal immunochemical test colorectal screening programmes in Italy

“…[31][32][33] Our study could not evaluate the seasonal variation of proportional incidence, however, the impact of warming on the frequency of interval cancers has been shown to be limited. 34 Moreover, some manufacturers of FIT recently modified the buffer of their products to prevent haemoglobin degradation at high temperatures. 35…”

Ambient temperature and FIT performance in the Emilia-Romagna colorectal cancer screening programme

“…Grazzini and colleagues 8 suggest that the differences between the two studies could be attributed to the significantly lower average temperature in the Netherlands, and that the relationship between ambient temperature and the degradation of the globin might have a non-linear relationship, with manifest effects even at low temperatures. Zorzi and colleagues 9 in a study of five screening centres in Italy found a higher incidence of interval cancers after tests that had been carried out in the summer compared with those performed in the winter. We investigated the influence of ambient temperature on the main early-impact indicators in the screening programme of Emilia-Romagna, a populous region of northern Italy (4,471,104 residents in 2012) with a sub-continental climate, significant annual temperature ranges, hot summers, and severe winters.…”