Toxoplasma gondii found in 100% of lung cancer tissue samples

[hei]

High frequency of infection of lung cancer patients with the parasite Toxoplasma gondii

Background Toxoplasma gondii is an intracellular protozoan parasite that can cause a wide range of clinical conditions, including miscarriage and pneumonia. The global prevalence is 30% in humans, but varies by locality ( e.g . in the UK it is typically 10%). The association between lung cancer...

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High frequency of infection of lung cancer patients with the parasite Toxoplasma gondii​

Jaroslav Bajnok, Muyassar Tarabulsi, Helen Carlin, Kevin Bown, Thomas Southworth, Josiah Dungwa, Dave Singh, Zhao-Rong Lun, Lucy Smyth, Geoff Hide

ERJ Open Research 2019 5: 00143-2018; DOI: 10.1183/23120541.00143-2018

Abstract​

Background Toxoplasma gondii is an intracellular protozoan parasite that can cause a wide range of clinical conditions, including miscarriage and pneumonia. The global prevalence is 30% in humans, but varies by locality (e.g. in the UK it is typically 10%). The association between lung cancer and T. gondii infection was investigated by direct detection in lung tissue samples.
Methods Lung tissue samples were taken from patients undergoing lung resection surgery (n=72) for suspected lung cancer (infection prevalence 100% (95% CI: 93.9–100%)). All 72 participants were confirmed as having lung cancer following subsequent diagnostic tests. In addition, bronchial biopsy samples were collected from non-lung cancer healthy control subjects (n=10). Samples were tested for T. gondii using PCR amplification of T. gondii specific gene markers and T. gondii specific immunohistochemistry.
Results All 72 lung cancer patients were infected with T. gondii (prevalence 100% (95% CI: 93.9–100%)). Of which, 95.8% (n=69) of patients showed evidence of active parasite stages. Infection prevalence in the controls (10%) was significantly lower (p<0.0001).
Conclusions Clinicians treating lung cancer patients should be aware of the potential presence of the parasite, the potential for induction of symptomatic complications and interference with treatment success.

 

[Ben.]

Wonder if this is one of these findings that shows that parasite follows damaged terrain/tissue or if it is causative.

 

[Perry Staltic]

Wonder if this is one of these findings that shows that parasite follows damaged terrain/tissue or if it is causative.

Probably opportunistic, not causative.. It's a ubiquitous parasite.

 

[amd]

That's the same argument for the Simian Virus 40, not being causative of cancer.

Summary:

Patients with cancer may have deficient cellular immunity that has allowed dysregulated proliferating cells to escape immune defences, and are potentially susceptible to opportunistic infections including T. gondii [5]. Not much is known about toxoplasmosis in this group of patients and few reports are available.

As examples of studies of T. gondii infection in cancer patients, serological measurement of infection rates showed high prevalences in nasopharyngeal carcinoma (46.2%) and rectal cancer (63.6%), but lower rates in the other cancer groups, for example, pulmonary carcinoma (4.6%), breast cancer (9.5%), gastric carcinoma (10.0%), hepatocellular carcinoma (14.3%) and uterine cervix carcinoma (12.5%).

This might suggest that there is an association between T. gondii infection and some types of cancer; however, these studies give little indication as to whether active infection is present, and they measure generic infection status rather than localised infection status in the cancer affected tissue.

The objectives of this study were to use specific DNA based and immunohistochemical detection systems to detect the presence of the parasite, T. gondii, in lung biopsy samples taken from a well-characterised collection of patients with lung cancer.

A secondary aim was to investigate any associations between parasite infection intensity or active/dormant infection and other recorded characteristics of these lung cancer patients (such as sex, age, presence of chronic obstructive pulmonary disease (COPD) and smoking history).