It is tough to answer this question and two more informations are required before I even attempt.

1. Cancer is not generic and different cancers have different drivers. So it is very important to understand which cancer we are talking about, because one must map that molecular pathway (s) to the active ingredient in ladies finger.

2. Ladies finger has multiple constituents. So the active ingredient (s) needs to be identified before we even try to understand its potency and efficacy.

Best Regards

Arnab

According to a research published in Nutrition Journal, lady’s finger has a higher concentration of antioxidants than most vegetables. These antioxidants prevent damage to cells from free radicals, and inhibit the growth of cancer cells in body.

Additionally, it contains some amount of insoluble fibre which promotes a healthy digestive tract and lowers your risk of colorectal cancer. Pectin present in the vegetable has been shown to prevent proliferation of melanoma cells in vitro.

You can find the details in the attached links with references. 

http://www.thehealthsite.com/fitness/health-benefits-of-ladys-finger-or-bhindi/

http://www.thealternativedaily.com/okra-goes-cancer-wins/

May be this article could be of some help.

Gul, M. Z., Bhakshu, L. M., Ahmad, F., Kondapi, A. K., Qureshi, I. A., & Ghazi, I. A. (2011). Evaluation of Abelmoschus moschatus extracts for antioxidant, free radical scavenging, antimicrobial and antiproliferative activities using in vitro assays. BMC Complementary and Alternative Medicine, 11, 64. http://doi.org/10.1186/1472-6882-11-64

OKRA CONTAINS  QUERCETIN ANALOGUE WHICH IS ANTICANCER. BELOW ARE THE REFERENCES 

Fruits and seeds of Abelmoschus esculentus L. (Lady's finger,Okra) containing phytochemicals, Carotene, Vitamin B & C and amino acids are reported to inhibit cancer growth.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4221879/

Thanks.

Thanks to all.

Dear Dr. Govind Pandey

Yes it works. Please have a look at these useful RG links and PDF attachments.

Article Studies on green synthesized silver nanoparticles using Abel...

Article The Role of Active Constituents of Abelmoschus esuslentus (O...

Article EVALUATION OF HEAMAGGLUTINATION AND ANTI-CANCER POTENTIAL FR...

Working Paper A PHYTOPHARMACOLOGICAL REVIEW ON ABELMOSCHUS ESCULENTUS LINN

Article Lectin of Abelmoschus esculentus (okra) promotes selective a...

Thanks!

May be you can useful from the following article