Infectious disease diagnoses often foreshadow cancer diagnoses

At a time when infectious diseases are front and center for medical researchers, a new study has emerged that lends more credence to the notion that the immune system response to these diseases can boost the patient’s risk for cancer. Seemingly counterintuitively, however, this retrospective study did not depict a direct relationship between the site of the infectious disease and the site of the cancer. The study was a seven-year, case-control study of residents of Japan aged 30 and older, and tracked the rates of diagnosis of influenza, gastroenteritis, hepatitis, and pneumonia. The control group consisted of nearly 48,400 and the case group was populated by more than 2,300 individuals who received a first diagnosis of cancer in the seventh year of the study. The authors said the yearly prevalence rates of the four communicable diseases each increased throughout the term of the seven years of the study, but the appearance of an elevated cancer risk varied between these four diseases. For instance, significant odds ratios were seen in only years two and six for influenza, but the authors said that for each cancer site, an increased rate of infection prior to cancer diagnosis was observed. They also said their analysis demonstrates increased infections “during the precancerous stage, a possible surrogate for tumor-induced immune suppression, correlated to eventual cancer development.” These results are reported in the May issue of Cancer Immunology Research.

Polymerase k and drug resistance

Scientists at Memorial Sloan-Kettering Cancer Center have demonstrated that polymerase k, an enzyme involved in error-prone DNA repair, was retained in the nucleus in cancer cells, where it contributed to cancer drug resistance. However, its DNA repair function might not be the mechanism by which it fostered drug resistance. As they divide at warp speed, tumor cells tend to acquire more mutations, and those mutations in turn can lead to drug resistance. The authors showed that in melanoma cell lines, treatment with the targeted therapy vemurafenib led to a stress response that included increased polymerase K expression in the nucleus, but that overexpression of polymerase k did not increase the mutation rate of tumor cells. “It is possible that Polk overexpression is mutagenic in our studies (and that those mutations contribute to the observed drug resistance) but that our technologies were not sufficient to quantify this. However, it is important to note that we cannot exclude other nonmutagenic functions of Polk that could account for the increased drug resistance,” the authors wrote. They reported their findings in the April 28, 2020, issue of Science Signaling.

Microcytosis link to cancer confirmed

Microcytosis is perhaps not the most studied of the blood disorders, but a recent study seems to offer support to previous research that draws an association between small red blood cells and cancer. A cohort study of more than 12,000 residents of the U.K. aged at least 40 years used a red blood cell volume of 85 femtoliters as the cut-off between low and normal red blood cell volume, and nearly 500 of these enrollees were diagnosed with a cancer within a year of enrollment, a diagnostic rate of roughly 4%. However, only 2% of the 73,000 controls who did not suffer from microcytosis were diagnosed with cancer. In one of the more conspicuous differences within the cancer-positive patients, 6.2% of men were diagnosed with cancer, substantially more than the 2.7% of microcytotic women who were also diagnosed with a cancer. On the other hand, microcytosis paired with normal hemoglobin seemed less prone to cancer, although men were again more susceptible (3.3%) than women (2.0%). The authors made their results known in the British Journal of General Practice.

Researchers describe new triple threat to cancer

Cancer does not always respond to a one-two punch, but researchers in China believe they have a follow-up blow that could knock out cancer. Many conventional approaches rely on the combination of photodynamic therapy (PTD) and chemotherapy, but the addition of ultrasound to these two approaches has not been well studied. The researchers made note of a “strong affinity” between sinoporophyrin sodium, a photosensitizer, and human serum albumin (HSA). This approach entails the use of an albumin-paclitaxel nanoparticle, which serves as a nano-glue for attaching the sinoporophyrin/HSA combination, and the two components can be combined “by simple mixing.” The researchers ran through five different conformations of the sinoporophyrin/HSA combination, and discovered that this combination provides improved fluorescence imaging and PTD performance than the free sinoporphyrin alone, perhaps due to reduced quenching as a result of dispersion in albumin. This combination was tested on breast tumor models implanted in mice, and observed significant inhibition of tumor growth. These results appear in the April 28, 2020, issue of ACS Nano.

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