New Light on the Treatment of Female Cancers

Metastatic cancer is often a lethal diagnosis.  Patients facing this situation typically undergo multiple cycles of chemotherapy, resulting in toxic side effects that either delay treatment or cause premature cessation of the treatment.  The problem of treatment resistance means that even with very high (and extremely toxic) doses, the treatments can be ineffective. Medical scientists have been interested in ways to enhance or potentiate chemotherapy treatments, as this could allow fewer treatment cycles and reduced toxicity. It is hoped that having access to less toxic, more immune-supportive treatments could help save many lives.

In this regard, photodynamic therapy, or PDT, is known to synergize with a number of chemotherapy drugs, essenitally making them more effective while lowering the overall toxic burden. In a recent experiment, scientists from the National Research Center in Cairo, Egypt, used the light-sensitizing precursor called 5-Aminolevulinic acid (ALA).  This natural substance is metabolized into protoporphyrin IX (PpIX), which preferentially accumulates in tumor cells, resulting in their destruction upon exposure to visible light.

One of the chemotherapy drugs commonly used to treat ovarian cancer is Doxil®, a nano-formulation of the drug doxorubicin. The Cairo study found that ALA/PDT had a synergistic effect against breast cancer cells when combined with low doses of Doxil chemotherapy, as reported in the June 2014 issue of Photodiagnosis and Photodynamic Therapy.

PDT for Recurrent Female Cancers

There is an urgent need for novel therapies for women with recurrent cancers, such as cancers of the breast, cervix and ovaries.  Researchers at Roswell Park Cancer Institute, in Buffalo, New York (USA), report their experience with PDT.  This approach involves a systemic injection of the photosensitizer Photofrin II, followed by exposure of the tumor tissue to visible light. The resulting photodynamic reactions damage the tumor’s vascular supply as well as the cancer cells themelsves, ultimately resulting in the tumor’s destruction.

Thirty-two women were included in the study.  The recurrent cancers included nine with cervical cancer, six with vulvar cancer, six with vaginal cancer, five with ovarian cancer, five with endometrial carcinoma, and one recurrent pagets of the anal canal.  All patients were treated with PDT, for a total of 45 treatment sessions. As reported in the European Journal of Gynaecological Oncology,  82% patients with metastatic cutaneous lesions had a complete response; in addition, 24% with vaginal, cervical or anal recurrences had a complete response to therapy. The side effects of treatment were limited to a burning sensation, pain, and edema at the treatment site.

The study concluded that PDT is an effective therapy in patients with recurrent female cancers and limited treatment options.  “PDT is an alternative therapy that offers the possibility of complete response in select groups of patient populations,” the authors concluded in their report. “Specifically, it provides palliation for superficial recurrent lesions of skin, cervix, vagina and vulva, in the absence of distant disease.”

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Sources

Zakaria S, Gamal-Eldeen AM, El-Daly SM, Saleh S. Synergistic apoptotic effect of Doxil ® and aminolevulinic acid-based photodynamic therapy on human breast adenocarcinoma cells. Photodiagnosis Photodyn Ther. 2014 Jun;11(2):227-38

Liu Y, Endo Y, Fujita T, Ishibashi H, Nishioka T, Canbay E, Li Y, Ogura SI, Yonemura Y. Cytoreductive Surgery Under Aminolevulinic Acid-Mediated Photodynamic Diagnosis Plus Hyperthermic Intraperitoneal Chemotherapy in Patients with Peritoneal Carcinomatosis from Ovarian Cancer and Primary Peritoneal Carcinoma: Results of a Phase I Trial. Ann Surg Oncol. 2014 Jul 24. [Epub ahead of print]

Guyon L, Farine MO, Lesage JC, Gevaert AM, Simonin S, Schmitt C, Collinet P, Mordon S. Photodynamic therapy of ovarian cancer peritoneal metastasis with hexaminolevulinate: A toxicity study. Photodiagnosis Photodyn Ther. 2014 Sep;11(3):265-74.

Godoy H, Vaddadi P, Cooper M, Frederick PJ, Odunsi K, Lele S. Photodynamic therapy effectively palliates gynecologic malignancies. Eur J Gynaecol Oncol. 2013;34(4):300-2.

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