Telomere Length Impacts Cancer Mortality

Longer telomeres gives cancer cells a survival advantage.

The mortality rate of cancer patients may be impacted by the length of repeated nucleotides that protect the end of chromosomes, according to a recent study.

Published in the April 10, 2015 issue of JNCI: Journal of the National Cancer Institute, the study examined how telomeres become shorter with each cellular replication before reaching a critical length, which can trigger the death of cells.

The enzyme telomerase restores the protective caps for sufficient replication in actively replicating cells, including embryonic stem cells and bone marrow blood stem cells. Cancer cells apparently can activate telomerase to allow it to divide indefinitely with negative outcomes for the patient.

The study evaluated how the extent of cancer cells to use telomerase may be dependent on which variants of genes related to telomerase activity are expressed within cells.

Though related to aging, telomere shortening can also be worsened by lifestyle factors, including obesity and smoking. Therefore, some previous studies have found a link between short telomeres and high mortality, while others did not find an association.

This conflicting evidence may be due to a correlational association between short telomeres and increased cancer mortality, while factors such as age and lifestyle that were not adjusted for in those studies were the real culprit, the study noted.

For the current study, researchers examined data from 2 prospective cohort studies that included 64,637 individuals followed from 1991 to 2011. The participants completed a questionnaire, had a physical examination, and had their blood taken for biochemistry, genotyping, and telomere length assays.

The researchers also utilized information on body mass index, blood pressure, cholesterol measurements, smoking status, alcohol consumption, physical activity, and socioeconomic variables.

The researchers used 3 single nucleotide polymorphisms of TERC, TERT, and OBFC1 to put together a score for the presence of telomere shortening alleles.

During the study, 7607 individuals died, with 2420 of these patients dying of cancer. The decreasing telomere length was linked with age and variables such as BMI, smoking, and with death from all causes, including cancer, the authors wrote.

A higher genetic score for decreasing telomere length was specifically linked to decreased cancer mortality, which indicates slightly shorter telomeres in cancer patients with a higher genetic score for telomere shortening may be beneficial.

"We speculate that long telomeres may represent a survival advantage for cancer cells, allowing multiple cell divisions leading to high cancer mortality,” the authors wrote.