What's Up Doc? Is Pagets disease a type of cancer?
A: In 1874 a physician named James Paget described a red, itchy, scaly rash (an eczematous rash) that he had identified on the breasts of 15 different women, all of which were associated with underlying breast cancer. Although only 1% to 5% of breast cancer patients also have Pagets disease, which itself is not a cancer, when there is Pagets disease of the breast there is usually an underlying breast cancer. So, Pagets disease of the breast seems to be a marker of possible underlying breast cancer. Over half of women presenting with Pagets disease of the breast (it is very uncommon in males) have a palpable breast tumor at presentation. Even when no mass is felt at the time of diagnosis of Pagets disease, 20% still have breast carcinoma in situ (localized cancer without invasion into nearby tissue) and 30% more will eventually develop breast carcinoma. The overall prognosis of Pagets disease of the breast depends on the presence and extent of any underlying cancer. Those with a palpable mass at presentation. which indicates they have more advanced disease, have about a 40% five-year survival rate, whereas those without a palpable mass have about a 90%t five-year survival rate. Although Pagets disease is most commonly diagnosed as Pagets disease of the breast, it can also be present in other locations; in this case the disease is called extra-mammary Pagets disease (EMPD). The cause of EMPD is not understood. EMPD is only associated with underlying cancer about 25% of the time, so it also not in and of itself a cancer diagnosis. It is thought that primary EMPD arises from the cells of apocrine glands (secreting glands, such as the sweat glands in the skin). The most common location of EMPD is the vulva (it is rarer in men, where it is most commonly on the scrotum), although it may affect the anal area, the axilla or other locations. However, vulva cancer accounts for only 5% of all genital cancers in women, and Pagets disease of the vulva represents only about 1% of all vulva cancers. So overall vulva cancers are uncommon, and Pagets disease of the vulva is a relatively rare disease. When it does occur, it is most common in women aged 60 to 70, although it can occur at any age. EMPD is suspected based on the characteristics of the rash and the symptoms, especially if these last for more than a month and do not respond to dermatitis (whose symptoms can be very similar) treatments. The diagnosis is confirmed by examination of a biopsy specimen. EMPD is treated by surgical excision, although other techniques (such as laser vaporization, chemotherapy, other treatments) may be used in circumstances where surgical excision cannot be done. The focus of the surgical excision is to remove the entire affected area, achieving "clean margins" (no evidence of disease in the outermost portions of the skin removed). However, even with appropriate surgical excision and margin control, EMPD recurs within two to three years in about a third of cases, requiring further treatment. The prognosis of EMPD depends on whether or not there is an underlying cancer. If there is underlying neoplasm, then the prognosis will align with the prognosis of the underlying cancer. However, if there is no underlying cancer and the skin disease is localized the overall prognosis is good, although if aggressive surgery is required the patients quality of life may be negatively impacted. Some cases of Pagets disease of the vulva have been documented to be present for 10 to 15 years without evidence of carcinoma or metastases. Women with an itchy rash should seek medical care, and if there is suspicion of Pagets disease a biopsy will likely be performed. The prognosis will depend on whether or not there is an associated underlying cancer. Even after appropriate treatment, close follow-up will be required to monitor for possible disease recurrence since the recurrence rate, as noted above, is substantial. Jeff Hersh, Ph.D., M.D., can be reached at DrHersh@juno.com