Imiquimod May Help to Prevent Vulvar Cancer

Key Words

Vulvar cancer, vulvar intraepithelial neoplasia (VIN), vulvar dysplasia, imiquimod ¹ (Aldara®). (Definitions of many terms related to cancer can be found in the Cancer.gov Dictionary.)

Summary

Women with a precancerous condition called vulvar intraepithelial neoplasia (VIN) were successfully treated with a drug that is applied to the affected areas as a cream. The drug, imiquimod (Aldara®), caused less discomfort and pain than standard surgical treatments. Although small, this study supports the conclusion that imiquimod should be the first-choice treatment for VIN.

Source

New England Journal of Medicine, April 3, 2008 (see the journal abstract ²).
(N Engl J Med. 2008 Apr 3;358(14):1465-73)

Background

Vulvar intraepithelial neoplasia (VIN) – also called vulvar dysplasia – is the abnormal growth of cells on the surface of the vulva, the outer part of the female reproductive system. It is not cancer, but it is considered a precancerous condition. Most cases of VIN are caused by persistent infection with the human papillomavirus (HPV).

Most women with VIN will not develop vulvar cancer. However, doctors cannot predict which cases of VIN are more likely to progress to cancer. For this reason, treatment of VIN is considered important for preventing vulvar cancer.

Surgery or laser ablation to remove the abnormal cells are standard treatments for VIN, but they have limitations. It is difficult to remove all of the abnormal cells. Even when all of the abnormal cells are removed, it is common for the disease to come back. Standard treatments do not eliminate HPV infection. Furthermore, they can mutilate the vulva, causing distress and difficulty with sexual intercourse.

Imiquimod is a drug that, when applied to affected areas as a cream, stimulates the immune system to kill abnormal cells. Preliminary studies had suggested that imiquimod might be an effective treatment for VIN.

The Study

Fifty-two women with VIN were enrolled in this study. They underwent biopsies to remove samples of abnormal cells, which were preserved for laboratory analysis. Then the women were randomly assigned to treatment with either imiquimod cream or an identical cream containing no active ingredient (a placebo). Neither the patients nor their doctors knew who was being treated with imiquimod and who was getting the placebo (called a double-blind study). Virtually all of the women (25 of 26 in each group) tested positive for HPV infection.

For 16 weeks, the women applied the cream to the affected area of the vulva twice weekly and left it there overnight, uncovered. They kept diaries to record side effects and use of other medications. They were checked by their doctors every four weeks. After 20 weeks they underwent biopsies again. Photographs were used to ensure that the post-treatment biopsy removed cells from the same site as the pretreatment biopsy. Patients were reassessed by their doctors after seven months and again after 12 months.

The study was led by Manon van Seters, M.D., of Erasmus University Medical Center in Rotterdam, the Netherlands.

Results

After 20 weeks, areas of abnormal cells (lesions) had shrunk by more than 25 percent in 21 out of 26 patients (81 percent) who were treated with imiquimod. Among these 21 patients, nine patients’ lesions disappeared and five patients’ lesions shrank by more than 75 percent. By contrast, in patients treated with a placebo no lesions shrank by more than 25 percent.

Fifteen of the women in the imiquimod group who had originally tested positive for HPV showed no signs of the infection at 20 weeks. In contrast, HPV infection cleared for only two of the women in the placebo group. In 69 percent of patients treated with imiquimod, VIN regressed to a lower (less serious) grade.

Treatment with imiquimod reduced itching and pain in the vulva. The nine patients whose lesions disappeared were still free of disease 12 months after treatment.

Comments

Imiquimod cream “is a promising agent for the treatment of [VIN],” the study authors conclude. “As a convenient, self-administered treatment, imiquimod is well tolerated, is less invasive than surgery, relieves itching and pain, and does not influence health-related quality of life, body image, or sexuality. Therefore, we consider imiquimod the first-choice treatment for [VIN].”

Ted Trimble, M.D., M.P.H., a gynecologic cancer specialist with the National Cancer Institute’s Cancer Therapy Evaluation Program, agrees. “Standard therapy for VIN may cause discomfort and chronic pain, as well as disfigurement,” he comments. “The results of this and other studies suggest that imiquimod should be used first.”

The small size of this study (52 patients) might be considered a limitation, adds Trimble. However, most VIN studies are small because it is a relatively rare disease. In the circumstances, Trimble believes the study, although small, is sufficient to support a definitive conclusion that imiquimod is an effective treatment for VIN.