A new study says retail prices for a number of brand-name prescription drugs used in treating skin conditions from cancer to acne, have dramatically increased over the last six years, according to a story on wsj.com.

The study was undertaken by Miranda Rosenberg, a third-year medical student at the University of Pennsylvania Pearlman School of Medicine, and her father, Stephen, a dermatologist in private practice in West Palm Beach, Fla. who also teaches at the University of Miami Miller School of Medicine.

The study looked at 19 different drugs, that averaged increasing five times in cost over a period covering 2009-2015.  The largest single increase was a drug from Valeant Pharmaceuticals called Targretin, which is used for treating a type of skin cancer.  The cost for a two-ounce tube of the gel in 2009 was $1,687 and jumped to $30,320 in 2015, an increase of 18 times the 2009 cost.  A different Valeant skin-cancer drug, Carac cream,  also increased to 18 times its 2009 cost.

Valeant has been in the headlines recently because of price increases on their products, but Rosenberg said the company was not the only one with the large increases, adding it was a phenomenon going on across the pharmaceutical industry.

Drug manufacturers counter that few patients of insurance companies actually pay the full retail prices, and their prices are often even more discounted by coupons, rebates and other programs.

But, the researchers say, the high list prices are still having an impact on the consumers wallet, as the insurance companies are looking to raise co-pays and deductibles based on the price lists they have.

Ms. Rosenberg said the initial focus of the study was not to expose the pricing increases from the drug companies, but to provide a database of drug costs for dermatologists in Florida when prescribing drugs for their patients.

Dr. Rosenberg said when the results came in, the increases made no sense, so they decided to put together an article in 2014, but by the time the article was accepted, they had received the 2015 data for inclusion.

He added that trends were similar for other medications as well, including generics.

The survey included information from four pharmacies close to her father’s practice, Costco, Walgreens, Sam’s Club and CVS, and included ass many as 120 drugs, but the report, published in journal JAMA Dermatology, focused on 19.