The new PLCO examination demonstration brings a unique and unequaled opportunity to prospectively and you may additionally evaluate these associations

1st maj 2022

The new PLCO examination demonstration brings a unique and unequaled opportunity to prospectively and you may additionally evaluate these associations

To our knowledge, no previous study has prospectively evaluated the associations of calcium intake with incident adenoma, metachronous adenoma, and incident cancer in the same cohort using the same food frequency questionnaire, which minimises misclassification that can occur when combining dietary estimates from multiple studies with different food frequency questionnaire instruments. One weakness is that the PLCO is a sigmoidoscopy-based randomised trial, which only screened the distal colorectal region. Thus, incident adenoma cases mainly included adenomas from the left side of the bowel although metachronous adenoma and incident CRC cases included cases from both proximal and distal regions. However, it is interesting that reports found that colonoscopy was linked to reduced deaths from the distal colorectal region, but not the right. 41,42 Similarly another report from the PLCO observed sigmoidoscopic screenings only reduced distal, but not proximal CRC mortality. 25 Further, sigmoidoscopic screenings also significantly reduced both distal and proximal CRC incidence in the PLCO. 25 Thus, the PLCO provides a unique opportunity to test whether calcium intake confers additional protection against proximal and distal CRC among those receiving sigmoidoscopic screening(s). Similar to other nutritional epidemiological studies using food frequency questionnaires, there are possibly non-differential measurement errors which usually bias the results to the null. In addition, despite the relatively large sample sizes in our study, our investigations between calcium intake and colorectal carcinogenesis were constrained when evaluating by Ca:Mg ratio strata. The number of cases for some sub-categories of calcium intake in the <1.7 Ca:Mg ratio stratum were few and in some instances zero, making inferences relating to trends difficult in this stratum. Furthermore, to maintain relatively balanced number of cases in calcium categories in the largest Ca:Mg ratio stratum, we choose 2.5, the median in the data set, as one of the Ca:Mg ratio cut-offs, instead of 2.6 as investigated in previous studies. Finally, considering investigation of three main outcomes, several sub-group analyses and tests for effect modification, it is possible that findings reported in this study may be due to chance. We found different calcium intake distribution between intervention arm and control arm shown in Supplementary Table 1. The reason is not clear, and it may be due to different food frequency questionnaires were in two arms. However, we found the association pattern between calcium intake and CRC risk is similar in the intervention arm and control arm.


The outcomes from our research have been in agreement which includes before had written education, however in disagreement with others. Both cohort studies and you will before intervention samples discovered highest calcium intake otherwise supplementation was related to sparingly smaller dangers of adenoma, metachronous adenoma and you can CRC. 7,8,9,ten,11,several,15,thirty-two But not, the outcomes from a massive-measure randomised clinical test (WHI) don’t help an effect of calcium supplements also vitamin D supplements for the chance away from CRC shortly after 7 years of follow-right up. 16 You'll be able to your realize-upwards months during the WHI might not have started long enough to have a defensive feeling getting apparent. Actually, the research of the Nurses' Wellness Study and you can Health professionals Follow-up Research not only showed an inverse association between calcium consumption and you may CRC and also revealed that new contacts turned into more and more more powerful having broadening episodes regarding latency, and was most effective into 12–sixteen decades realize-right up period. 33 With the average go after-right up period even more such as this studies compared to the WHI, i too declaration similar area rates due to the fact Zhang et al., which have a more powerful inverse connection to possess distal CRC but not for proximal CRC. 33 A pooled-research away from ten cohort education along with said the inverse association ranging from whole milk and you will CRC are limited to malignant tumors of distal, perhaps not the fresh proximal rectum. 15 For this reason accumulating facts constantly indicates calcium consumption are for the smaller risk of distal CRC.

Metachronous colorectal adenoma (recurrent adenoma)

It is distinguished when we analyzed brand new joint connectivity from California consumption with Milligrams consumption classified from the RDA top for a few different kinds of colorectal neoplasia risk (incident adenoma, experience CRC or experience distal CRC), i found comparable fashion such as the top analyses where in actuality the inverse associations to have Ca consumption about these types of effects was basically all of the healthier for Mg consumption at the or over the RDA opposed so you can Mg consumption lower than the RDA (Supplementary Dining tables cuatro–6). Although not, none of one's evaluating to have telecommunications was in fact mathematically high conversely toward evaluation getting correspondence i noticed towards California:Milligrams percentages. This is consistent with prior conclusions for the Eastern Asian populations in the that your connections was indeed statistically tall between California:Mg rates that have calcium supplements intake, however between magnesium intake with calcium supplements intake. 19 Put another way, the new interaction with Ca:Milligrams ratios can't be told me of the magnesium intake alone.