Critical Analysis of an Article


CriticalAnalysis of an Article

CriticalAnalysis of an Article

Willeit,P., Willeit, J., Mayr., A., Weger, S., Oberhollenzer, F.,Brandstatter, A., Kronenberg, F &amp Kiechl, S (2010). TelomereLength and Risk of Incident Cancer and Cancer Mortality. JAMA,Vol. 304. No. 1.

Thisarticle describes a research study that was carried out in an effortto determine the relationship between the length of telomere andcancer incident and mortality. It was based on the recognition of thecrucial nature of telomeres in the preservation of the integrity ofgenomes. Indeed, research has shown that telomeres, which underlinethe microprotein complexes found at the extreme ends of linearcomplexes and implicit in maintaining the integrity of chromosomes,often shorted with every cell cycle. This comes as evidence of theaging of organisms at the cellular level. However, there arevariations in the manner in which healthy and unhealthy cells reactto the shortening of the telomere length. It is noted that cellsundergo replicative cell senescence at critically short telomerelength, while malignant cells reactivate and over-express enzymetelomeres responsible for the lengthening of the telomere and enablesnumerous divisions. This study acknowledges the limited nature ofassessments or data on cancer mortality, both in terms of the typesof groups used in studies or type of research design. The hypothesis,in this case revolves around the fact that telomere attritioncontributes to the dissemination and manifestation of malignancies.


Inthis study, a total of 826 men and women who had served in the 1995evaluation were included, 39 of whom were eliminated as a result ofmissing DNA and presence of cancer. The remaining participants hadtheir data taken through complete follow-up for clinical endpointsfrom 1995 to 2005.All the participants went through anall-inclusive laboratory and clinical examination, with venous bloodsamples being taken after participants abstained from smoking for 12hours and fasted overnight (Willeit et al, 2010). DNA extraction wascarried out using standard procedure by Invisorb Blood Universal Kit,while the length of leukocyte telomere was measured using PCRtechnique. On the same note, the reaction efficiencies were determine by the use of the fluorescence increase steepness in thecourse of quantitative PCR cycles and used to calculate the T/S ratiovariations between individuals and genes in efficiency. The length oftelomere was measured in quadruplicate for both 1995 and 2005samples. To account for variation in interpolate measurement,standard DNA on every quantitative PCR plate was located.


11.7percent or 92 out of 787 participants developed cancer within the tenyear period. This study also showed that short length of telomere atbaseline is related to cancer incident independent of the standardrisk factors of cancer. In addition, short length of telomere wasrelated to cancer mortality, as well as individual cancer subtypesthat have a high fatality rate. Of particular note is the fact thatthe association was equally applicable to women and men and came upas immensely robust in certain circumstances. The baseline length oftelomere was considerably shorter in participants with cancerincident than in individuals who were free of cancer.


Whilethe results of this study may have been considerably crucial toot hedetermination of the association between cancer incidence andmortality rates, it is worth noting that the population used in thisstudy was entirely limited. In this regard, the population wasentirely white, in which case the results of this study would not benecessarily be extrapolated to other ethnicities or races (Willeit etal, 2010). On the same note, the characteristics of the populationmay be compared to those in other western communities but it isunknown whether the findings may be transferred to other geographicalregions that have distinct or unique genetic backgrounds. Further, asmuch as the study was sufficiently powered to evaluate therelationship between the telomere length and both the mortality andincidence of cancer, the number of cases were restricted to 44 and 92respectively (Willeit et al, 2010). This underlines the fact thatsize of the sample was too small to make a precise evaluation of theassociation between the length of telomere and every specific type ofcancer. On the same note, it is likely that there are other forms ofheterogeneity beyond the fatality of the cancer, which has not beenaddressed in the article or the study at large. Of particular note isthe fact that the data used in classifying tumors as non-fatal orfatal was collected in the course of the last follow-up examinationin 2005, in which case there are high chances that it would berefined in later times. Further, rather than use varied distincttissues in measuring the length of telomere, the researchers usedeasily accessible sources of DNA in their study.


Oneof the most fundamental lessons provided in the article revolvesaround the fact that the aging of leukocytes shown in short telomerelength may not only impair the immune surveillance but also lower theclearance or tumor cells. Indeed, the reduced immunity in AIDspatients resulted in excess incidence of tumors. On the same note,the relationship between short length of leukocyte telomere andformation of cancer is mediated in part by the immune system aging.Needless to say, the article has been written very well with ideasbeing arranged in a logical manner to allow for proper comprehensionof the ideas presented. Nevertheless, it would have been preferablethat the researchers include people from varied ethnic and racialbackgrounds so as to eliminate the uncertainty regarding theapplicability of the results to other races.


Willeit,P., Willeit, J., Mayr., A., Weger, S., Oberhollenzer, F.,Brandstatter, A., Kronenberg, F &amp Kiechl, S (2010). TelomereLength and Risk of Incident Cancer and Cancer Mortality. JAMA,Vol. 304. No. 1.