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Surgical chemotherapy against lymph node metastases: an experimental study
Abstract:
Accompanying surgical resection of the primary tumor is removal of its drainage lymph nodes. However, all of the minute regional lymph nodes cannot be identified and some may be left behind. If a certain anticancer agent in the form of an emulsion is injected topically into the lymph nodes, it may suppress the lymphatic metastases. Domestic rabbits were used as experimental animals, because transplantable VX2 tumors are available. The vermiform appendix was selected as the transplantation site because of its rich supply of lymph follicles, simulating lymph nodes histologically, and because the path of lymph drainage is very simple. The drainage lymph node, which is located at the root of the appendix, was selected for study. The rate of transfer of bleomycin into lymph nodes and of its sustained release from the nodes was extremely enhanced by the use of a sphere-in-oil-type emulsion--more than two times higher than in the use of a W/O emulsion. Although prolongation of survival time did not take place in animals receiving the bleomycin solution topically or intravenously, five of the seven rabbits receiving the local administration of bleomycin as a sphere-in-oil or a water-in-oil emulsion, between which differences were not found in tumor effects, survived with complete reduction of the lymph node metastases.
Insights
Topical anticancer emulsion effectively targets lymph node metastases. Local bleomycin emulsion administration in rabbits led to complete reduction of lymph node tumors and survival in most subjects.
Area of Science:
- Oncology
- Pharmacology
- Surgical Oncology
Background:
- Surgical resection of primary tumors often leaves microscopic lymph node metastases undetected.
- Effective suppression of lymphatic spread is crucial for improving cancer patient outcomes.
- Topical delivery of anticancer agents to lymph nodes presents a potential strategy to combat micrometastases.
Purpose of the Study:
- To evaluate the efficacy of bleomycin emulsions for topical delivery to lymph nodes in suppressing lymphatic metastases.
- To compare the lymphatic transfer and sustained release of bleomycin using different emulsion types.
- To assess the impact of local bleomycin administration on lymph node metastasis and survival in a rabbit model.
Main Methods:
- VX2 tumors were transplanted into the vermiform appendix of domestic rabbits.
- Bleomycin was formulated into sphere-in-oil (S/O) and water-in-oil (W/O) emulsions for topical administration.
- Lymphatic transfer, sustained release, and tumor reduction in the drainage lymph node were analyzed.
- Survival rates of rabbits receiving different bleomycin formulations and administration routes were compared.
Main Results:
- Sphere-in-oil (S/O) emulsion significantly enhanced bleomycin transfer and sustained release into lymph nodes compared to W/O emulsion.
- Local administration of bleomycin as S/O or W/O emulsion resulted in complete reduction of lymph node metastases in 5 out of 7 rabbits.
- No survival prolongation was observed with topical or intravenous bleomycin solutions.
Conclusions:
- Topical bleomycin delivered via S/O or W/O emulsions is effective in eradicating lymph node metastases.
- Emulsion-based topical delivery enhances bleomycin's lymphatic transfer and sustained release, improving therapeutic potential.
- Local administration of anticancer emulsions offers a promising approach for managing lymphatic spread in cancer.