Patients with stage I malignant melanoma have cancer that is found in the outer layer of the skin (epidermis) and/or the upper part of the inner layer of skin (dermis), but has not spread to lymph nodes. The primary melanoma is less than 2 millimeters (1/16 of an inch) thick.
The following is a general overview of treatment for stage I melanoma. Circumstances unique to each patient’s situation may influence how these general treatment principles are applied. The potential benefits of multi-modality care, participation in a clinical trial, or standard treatment must be carefully balanced with the potential risks. The information on this website is intended to help educate patients about their treatment options and to facilitate a mutual or shared decision-making process with their treating cancer physician.
The most important initial feature that is obtained from biopsy at the time that the melanoma is diagnosed is the thickness of the melanoma (Breslow thickness, measured in millimeters). A pathologist determines this thickness by examining the melanoma under a microscope and measuring the lesion from the top to the bottom. The actual size of the melanoma on the skin provides little information. Based on the thickness of the tumor, melanoma is divided into 3 general categories:
- Thin melanomas, which are less than or equal to 1 mm in thickness
- Intermediate thickness melanomas, which are between 1 mm to 4 mm
- Thick melanomas, which are greater than 4 mm
The thicker a melanoma is determined to be at the time of diagnosis, the greater the chance that it has spread to sites beyond the initial tumor. In general when melanoma spreads, it spreads to lymph nodes in the region of the primary tumor first.
In addition to thickness, there are other features that can determine the “aggressiveness” or likelihood that the tumor has spread. Microscopic absence of the continuous epidermis in the tissue overlying the melanoma, which is referred to as ulceration, is recognized as a particularly important prognostic factor for melanoma of any thickness. Other features that are relevant, primarily for patients with thin melanomas, are vertical growth phase, penetration to Clark Level IV (invades deeper through the dermis, but still contained completely within the skin), and regression.
The standard treatment of stage I melanoma is surgical removal with pathologically confirmed negative margins. Historically, a very wide area of normal skin was removed along with the primary melanoma. This often led to disfigurement and required skin grafting. More recently, an effort has been made to reduce the amount of normal skin removed without compromising the cure rate achieved with surgery. Melanoma greater than 1 millimeter appears to require a greater surgical margin to reduce the rate of recurrence at the site of origin. Most surgeons recommend a surgical margin of 2 centimeters (almost an inch) surrounding the entire cancer for melanomas greater than 1 mm. The need for skin grafting occurs in approximately 10% of patients. Surgical margins greater than 2 cm are no more effective and require skin grafting in a higher fraction of patients (up to 50%).
Both the American Joint Committee on Cancer and the World Health Organization recommend evaluation of the regional lymph nodes by performing a sentinel lymph node (SLN) biopsy as a staging procedure for patients with a primary melanoma greater than 1 mm. In addition, recent guidelines for sentinel lymph node biopsy include patients with thin melanomas (< 1 mm) with adverse prognostic factors, such as vertical growth phase, Clark Level IV, regression, and ulceration.
The surgical treatment of stage I melanoma typically involves a single procedure in which a local excision of the cancer is performed as well as a SLN biopsy. During a SLN biopsy, a physician injects a tracer (radioactive isotope and/or blue dye) into the area of the primary tumor. The tracer, which is taken up by the lymph system, identifies the so-called "sentinel lymph node”, which is the first lymph node that could be potentially involved with melanoma. Lymphatic mapping can be performed prior to surgery to aid the physician in determining which lymph node group is the primary drainage basin for any particular area of skin and it can also be used on the day of surgery to identify which lymph node is the “sentinel” lymph node.
Once the SLN has been identified, the physician removes the SLN through a small incision and then a pathologist examines the SLN under the microscope to detect whether or not there is any evidence of melanoma cells. Patients who have a positive sentinel node (tumor identified) are counseled to undergo removal of all the lymph nodes in the region, while patients who have a negative sentinel node do not undergo further surgery. Approximately 15% of patients undergoing SLN biopsy have a positive SLN (pathologically stage III). Ninety-five percent of patients with a confirmed negative "sentinel node" are free of cancer and require no additional treatment.
In general, over 90% of patients with melanomas of less than 1 mm are cured following surgical removal of the melanoma. In one study evaluating surgical treatment of 602 patients with melanoma 0.75 mm or less in thickness, only 4% of patients experienced a recurrence. In another clinical study of patients treated at the Mayo Clinic, the 5-year survival rate for stage 1 melanoma of 0.75 mm or less was 98%.
The exact rate of cancer recurrence in patients with stage I melanoma is not well defined because the confirmation of negative lymph nodes using the sentinel lymph node technique has only recently been widely adopted. Studies that accrued patients prior to the 1990s reported recurrence rates of approximately 15%.
Patients with melanoma of less than 1 millimeter should ask their physicians whether or not their melanoma demonstrated any evidence of ulceration, vertical growth phase, regression, or whether it is Clark level IV. Patients should also inquire about the treatment results achieved at the cancer center or institution where they are considering treatment.
The progress that has been made in early stage melanoma has resulted from the improved ability to accurately stage patients by detecting small amounts of tumor that have spread to lymph nodes. Patients with confirmed stage I disease are adequately treated with surgical resection of the primary tumor and when appropriate, confirmation of negative sentinel lymph nodes by sentinel lymph node biopsy.
Adjuvant Therapy: Despite undergoing sentinel lymph node evaluations, some patients with melanoma have small amounts of cancer that have spread into the lymph nodes and were not detected. Undetectable areas of cancer are referred to as micrometastases. The presence of micrometastases causes cancer recurrence following treatment with surgery alone. An effective treatment is needed to cleanse the body of micrometastases in order to improve a patient's duration of survival and potential for cure. The delivery of cancer treatment following local treatment with surgery is referred to as "adjuvant" therapy.
Clinical studies evaluating adjuvant therapies following surgery in stage I melanoma have currently not demonstrated an improvement in survival. A randomized trial that directly compared adjuvant alpha interferon to no additional treatment failed to show any advantage for the administration of alpha interferon (3 times a week for 12 weeks) in preventing melanoma recurrences in patients with stage I melanoma.