• Are specific to or more prominent in tropical areas such as Burkitt's lymphoma or Kaposi's sarcoma.

• Have etiological factors found more frequently in tropical areas such as aflatoxins produced by molds in peanuts, which under different culinary preparations constitute an important part of the daily diet of many Africans. Aflatoxins are involved in the genesis of primary liver cancer, which is highly prevalent in tropical countries.

• Have a positive progression in many tropical countries whereas the opposite trend can be observed in some developed countries as for cancer due to smoking. This divergent evolution is largely due to (a) Aggressive marketing strategies of cigarette companies in third world countries and (b) Very restrictive government regulations in first world countries.

• Emerge in the course of AIDS (a disease which originated in the tropics), such as Kaposi's sarcoma, cerebral lymphoma and non-Hodgkin lymphoma.

• Can lead to cancer such as bladder cancer in urinary schistosomiasis.

• Have cancer-like local evolution such as echinococosis or metastatic progression such as hydatidosis, when the cyst is ruptured.

• Can be found in patients immuno-depressed by cancer or its therapy such as candidiasis, disseminated aspergillosis, cryptococcosis, pneumocystosis, cryptosporidiosis, microsporidiosis, malignant strongyloidiasis, etc…

However, to this date the complementarity and overlapping of cancer and tropical disease research have been largely underestimated. Although they are both conducted first and foremost in developed countries, the reasons for this fact may be multiple, for example:

While cancer patients reside primarily in first world countries, tropical disease patients overwhelmingly live in third world countries. These populations are further divided geographically: mainly in the Northern Hemisphere for cancer and in the Southern Hemisphere for tropical diseases. Other gaps separate them such as (a) Age: globally older for cancer and younger for tropical diseases and (b) Wealth: rich in the North and poor in the South.

Tropical Diseases Departments

Cancer Centers

Mutual ignorance

Although well tolerated and efficient in humans and widely used in amebiasis, giardiasis, trichomoniasis and anaerobe infections, it has been shown to significantly increase the incidences of lung tumors in mice of each sex, lymphomas in female mice[₁,₂] and mammary, pituitary, testicular and liver tumors in rats[₁,₃,₄]. It also increases the incidence of colonic tumors induced in rats by subcutaneous administration of 1,2-dimethylhydrazine[₅,₆].

It is an important drug for treating systemic mycoses such as candidiasis, cryptococcosis, chromomycosis and aspergillosis. After administration, it is metabolized intracellularly into 5-fluorouracil by a specific deaminate cytosine enzyme[₇]. Fluorouracil itself can be used against digestive tract adenocarcinomas, colorectal cancer, breast and ovarian cancer and squamous cell carcinomas of the upper respiratory and digestive tracts[₇].

It is very efficient and well tolerated, even after the first trimester of pregnancy and was used in ascariasis[₈]. It is also partially active in ancylostomiasis. In mice, its antitumor effects are mediated by NC-1.1+ cells[₉]. The FDA has approved it in combination with 5-fluorouracil in the treatment of Duke's stage C colon cancer[₁₀].

It is well tolerated and very efficient against Schistosoma haematobium, Schistosoma mansoni and Schistosoma intercalatum[₁₁]. It has cancer anti oxidant protective actions associated with the induction of two enzymes mediated by a 41bp enhancer. It induces superoxide formation[₁₂].

Widely used in HIV/AIDS, these compounds have other therapeutic properties:

• In cancer: Nelfinavir induces endoplasmic reticulum stress, autophagy and apoptosis in vitro and in vivo (in mice). Nelfinavir, Ritonavir and Saquinavir inhibit the proliferation of NSCLC cells as well as every cell line in the NC160 cell line panel. Nelfinavir is the most potent. It also decreases the viability of drug resistant breast cancer cells lines[13].

• In Chagas disease[14]:A cysteine protease inhibitor has been shown to protect dogs from cardiac damage during infection by Trypanosoma cruzi[15]. Furthermore, it can cure T. cruzi experimental infections in mice[16].

It is a drug of choice in the treatment of chronic hepatitis C and B (the latter being the most endemic in Africa and Southeast Asia). It is also indicated in hairy cell leukemia, follicular lymphomas, and malignant melanoma in the USA[₁₇] and chronic myeloid leukemia, multiple myeloma and carcinoid tumors in France[₇]