Beyond Actinic Keratosis: Promising Outlook for Diclofenac Gel for Skin Cancer Treatment
If you tend to put diclofenac into a neat little treatment box, compounding it primarily for pain relief, it’s time to take a fresh look at this dynamic drug. Topical diclofenac sodium gel 3 percent safely and effectively heals actinic keratosis, making it a solid therapeutic option compounding pharmacists can recommend when counseling patients. Curing actinic keratosis is essential for preventing skin cancer, but that’s not all it can do. Diclofenac is poised to step into the realm of cancer treatment.
“It’s somewhat surprising that there is still so much we don’t understand about how many of the standard drugs we use every day, like diclofenac, work,” says Pan Pantziarka, PhD., of the Repurposing Drugs in Oncology project. But based on the current evidence, the project hopes diclofenac will move into clinical trials to further its role in cancer treatment.
Efficacy of Diclofenac Gel for Treating Actinic Keratosis
Long-term exposure to ultraviolet light produces one of the most common skin lesions with malignant potential—actinic keratosis. It’s estimated that actinic keratosis lesions will progress to cancer in up to 10 percent of patients, but more importantly:1
- 65 percent of primary squamous cell carcinomas arise from actinic keratosis
- 36 percent of primary basal cell carcinomas began as actinic keratosis
Since actinic keratosis responds well to treatment and progression to cancer can’t be predicted, early identification and diagnosis are essential. While several topical treatments are effective they’re also known to cause significant side effects. Diclofenac gel 3 percent is equally effective and better tolerated with a low rate of mostly mild side effects. It’s a good option for many patients, but especially for the 23 percent who stop their treatment due to adverse events.
Diclofenac 3 percent was approved by the FDA to treat actinic keratosis more than a decade ago. Since then, emerging research has continued to report encouraging news. In 2009, a study published in the Journal of Clinical and Aesthetic Dermatology looked at its long-term efficacy.2 Patients in a Phase 4, multicenter trial used diclofenac sodium gel 3 percent twice daily for 90 days. Those who completed the original study without needing further treatment for their actinic keratosis then participated in an extended study to measure lesion clearance at the end of one year. The results were impressive:
- 81 percent didn’t need any treatment in the year following their diclofenac regimen.
- 91 percent of patients had 75 percent clearance of target actinic keratosis lesions after one year.
- 70 percent had 100 percent clearance at one year for target lesions.
- Conclusion—a 90-day course of diclofenac sodium 3 percent gel persisted in 96 percent of patients at one year.
Since then studies have shown that diclofenac sodium gel 3 percent has comparable efficacy with 5-fluorouracil 5 percent and imiquimod 5 percent. It’s also effective for clearing lesions in immunosuppressed people. In its role as an anti-inflammatory and analgesic agent, diclofenac is known to block the effect of COX enzymes, but studies show it also inhibits angiogenesis and induces apoptosis.3
Repurposing Topical Diclofenac to Treat Cancer
The Repurposing Drugs in Oncology (ReDO) project put diclofenac in the headlines as a promising candidate in the fight against cancer—and not just for its preventive role by healing actinic keratosis. The experts at ReDO noted that diclofenac’s multiple mechanisms of action—particularly its effect on angiogenesis and the immune system—give it huge potential to treat cancer. They recommended starting clinical trials based upon reviewing the results of many studies, such as:4
- Diclofenac reduced tumor blood flow and tumor growth in rats with fibrosarcoma.
- Tumor growth was inhibited or stopped when diclofenac was applied to colon-26 adenocarcinoma tumors, pediatric neuroblastoma cells, and prostate, ovarian and pancreatic cancer cell lines.
Treatment for Basal Cell Carcinoma:
Topical diclofenac gel 3 percent also shows promise for treating basal cell carcinoma, according to the results of a phase 2, randomized controlled trial published in the Journal of the American Academy of Dermatology.5 A group of researchers from Maastricht University Medical Center in the Netherlands randomized 64 patients with superficial basal cell carcinoma (sBCC) into four groups receiving topical diclofenac sodium gel 3 percent, calcitriol 3 micrograms/gram ointment, a combination of both, or no topical treatment.
After twice-daily treatment for eight weeks, the sBCC group treated with diclofenac showed a significant decrease in tumor proliferation as measured by Ki-67. Complete histologic tumor regression was seen in 64 percent of patients using diclofenac and 43 percent of those using combination therapy, compared to no regression in controls. Additionally, adverse reactions at the site of application were only mild to moderate. Of course, the sample size was small and more studies are needed to verify the results, but it’s exciting to look forward to the value of adding diclofenac to the anti-cancer lineup, especially since its mode of action is different from other noninvasive therapies for sBCC.
Feature Diclofenac in the Treatment Toolbox for Patient Health
More than 58 million people are estimated to have actinic keratosis, yet many don’t realize they’re at risk for skin cancer until the slowly developing spots turn into the more menacing red or brown crusty spots, sometimes growing tiny horns that project out from the skin.6 As a compounding pharmacist you have a vital role, as you can alert patients about the urgency of early diagnosis and treatment. More importantly, you can ensure patients get optimal results by encouraging treatment adherence—a task that’s easier with topical diclofenac gel 3 percent.
Pharmaceutica North America is proud to feature diclofenac sodium gel 3 percent among our line of diclofenac pharmaceuticals, which includes diclofenac sodium solution 1.5 percent as an FDA approved finished product. Contact us today to talk about how our products can help meet the needs of your patients.
- “Actinic Keratosis,” April 2016, http://emedicine.medscape.com/article/1099775-overview ↩
- “Long-Term Follow-Up of Diclofenac Sodium 3 Percent in 2.5 Percent Hyaluronic Acid Gel for Actinic Keratosis: One-Year Evaluation,” July 2009, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2924138/ ↩
- “Diclofenac Sodium 3 Percent Gel for the Management of Actinic Keratosis: 10+ Years of Cumulative Evidence of Efficacy and Safety,” May 2012, http://www.ncbi.nlm.nih.gov/pubmed/22527428 ↩
- “Repurposing Drugs in Oncology—Diclofenac as an Anti-Cancer Agent,” January 2016, http://ecancer.org/journal/10/full/610-repurposing-drugs-in-oncology-redo-diclofenac-as-an-anti-cancer-agent.php ↩
- “The Effect of Topical Diclofenac 3 Percent and Calcitriol 3 Micrograms/gram on Superficial Basal Cell Carcinoma (sBCC) and Nodular Basal Cell Carcinoma (nBCC): A Phase II, Randomized Controlled Trial,” April 2016, http://www.ncbi.nlm.nih.gov/pubmed/27067393 ↩
- “Actinic Keratosis,” 2016, http://www.skincancer.org/skin-cancer-information/actinic-keratosis#sthash.r6lhP9wk.dpuf ↩