Spontaneous regression of tumour and the role of microbial infection – possibilities for cancer treatment

Abstract

This review deals with the role of microorganisms in spontaneous regression of a tumour. Spontaneous cancer regression is a phenomenon that has been described for many centuries. One of the most well known methods of inducing spontaneous regression of cancer is the application of Coley’s toxin (heat-killed Streptococcus pyogenes and Serratia marcescens), which has been used for the successful treatment of sarcomas, carcinomas, lymphomas, myelomas and melanomas. In clinical practice, the use of Bacillus Calmette-Guérin vaccine for the treatment of superficial urinary bladder cancer is the most common instance of the application of microorganisms for the treatment of cancer. This review provides further information on other tested bacteria – Clostridium spp., Bifidobacterium spp., Lactobacillus spp. and Salmonella spp. – in this field of study. Among new age methods, bactofection, alternative gene therapy, combination bacteriolytic therapy and bacteria-directed enzyme prodrug therapy are some of the potential cancer treatment modalities that use microorganisms. We have also provided information about the interconnection among microorganisms, immune system response, and the possible mechanisms involved in the spontaneous regression of tumours.

Chlamydia trachomatis Seroprevalence and Ultrasound-Diagnosed Uterine Fibroids in a Large Population of Young African-American Women

“…There has long been substantial evidence that bacterial infections can lead to the spontaneous regression of some tumors (34). The infecting organism could directly induce antitumor effects, or the infection could lead to enhancement of immune surveillance (34). Altough little is known about gCT infection of the uterus, especially the myometrium, finding gCT in the upper genital tract is not uncommon (7,8); the association between gCT and pelvic inflammatory disease is very well known (35).…”

“…There has long been substantial evidence that bacterial infections can lead to the spontaneous regression of some tumors (34). The infecting organism could directly induce antitumor effects, or the infection could lead to enhancement of immune surveillance (34).…”

Cancer immunotherapy: a brief review of the history, possibilities, and challenges ahead

“…It has been known for many years that the immune system plays a major role in neoplastic development and control, since patients who are immunosuppressed have a higher risk of cancer, and spontaneous regression of many types of malignant tumors is a rare but wellrecognized phenomenon-occurring in approximately 1 in every 60,000 to 100,000 cancer cases [8][9][10] .…”

Preclinical efficacy and safety of the Ty21a vaccine strain for intravesical immunotherapy of non-muscle-invasive bladder cancer

“…23 Beside BCG, other bacteria, including Salmonella, but not Ty21a, have been tested in the past for their potential in anticancer treatment. 24 However, the effects of these bacteria were rather associated to their reported capacities to target and multiply in the hypoxic tumor-microenvironment at the detriment of the tumor-cells themselves, than to a potent inflammatory reaction as could be observed with the historical Coley's toxin. 24 Induction of tumorcell death, innate and adaptive immune responses by Ty21a is thus in the same therapeutic line as BCG-immunotherapy.…”

“…24 However, the effects of these bacteria were rather associated to their reported capacities to target and multiply in the hypoxic tumor-microenvironment at the detriment of the tumor-cells themselves, than to a potent inflammatory reaction as could be observed with the historical Coley's toxin. 24 Induction of tumorcell death, innate and adaptive immune responses by Ty21a is thus in the same therapeutic line as BCG-immunotherapy. The absence of Ty21a bacterial survival in our experiments is in agreement with previous data reporting absence of Ty21a recovery and/or survival from human intestine and blood in vivo (reviewed in ref.…”