A SAMPLE FROM THE MOSS REPORTS:
TREATMENT OF ANORECTAL MELANOMA
You have asked for a report on anorectal melanoma. I shall discuss this topic, move on to a discussion of the conventional approach to melanoma in general, and then discuss some of the most promising alternative and complementary treatments.
INCIDENCE: Anorectal melanoma is a rare cancer. It constitutes less than one percent of all anal tumors (cancers of the outlet of the bowel). There were 3,400 cases of cancer of the anus, anal canal and anorectum in the U.S. in 1997, but most of these were of the squamous cell variety. There were just a few dozen cases of anorectal melanoma in that same year. A big cancer center such as Memorial Sloan-Kettering in New York averages only about two such cases per year (Dis Colon Rectum 1995;38:146).
This type of cancer typically strikes people in their fifties and is somewhat more common in women than men. The most common symptom is rectal bleeding. This is often attributed to hemorrhoids. Other symptoms include pain, itching, changes in bowel habits, and unexplained weight loss.
DIAGNOSIS: Anorectal melanoma is notoriously difficult to diagnose, since the initial complaints that bring a patient to the doctor are the same as for many other conditions. For this reason, the disease is incorrectly diagnosed in about 80 percent of cases. This accounts for the fact that, when discovered, anorectal melanoma is generally found in a fairly advanced state.
Sometimes the disease is diagnosed when melanoma cells are found in a hemorrhoid specimen removed and biopsied as part of the treatment of that benign conditon. Although we think of melanoma as a pigmented (black) cancer, the anal mass is pigmented in only one third of cases.
SIZE: For the aforementioned reasons, anorectal melanoma tumors tend to be relatively large when discovered, for example between 3 and 5 centimeters. They can be as large as 12 centimeters. Affected groin (inguinal) lymph nodes can be palpated (detected by touch) in about 20 percent of the cases. In addition, the more interior mesenteric nodes are found to be involved with cancer in 65 percent of the patients who eventually undergo radical surgery.
MORPHOLOGY: Under the microscope, the cells that cause anorectal melanoma are virtually identical to those involved in melanoma of the skin. This gives us a hint as to their proper treatment. Despite their differences, any systemic treatment should probably be the same as for cutaneous (skin) melanoma.
Anorectal melanomas tend to spread locally into the rectum, but they rarely invade the bladder, vagina, sacrum or the prostate.
SURVIVAL: This is a tumor with a notoriously poor prognosis, at least when the treatment is restricted to the conventional triad of surgery, radiation and chemotherapy. Several recent studies from different parts of the world have shown that the overall five-year survival of patients with anorectal cancer is 21 to 22 percent, while the disease-free survival is around 16 percent (J Chir [Paris] 1997;134:3; and Dis Colon Rectum 1997;40:661).
In a retrospective study, Memorial Sloan-Kettering scientists found that since 1929, the survival of 85 treated patients was 17 percent at five years, with a median survival of 19 months. This seems to indicate that there has been an increase in five-year survival of perhaps five percent over the decades. This improvement may be a statistical fluke, or it may indicate lower mortality and morbidity from surgery. There have been no big breakthroughs in the treatment of anorectal melanoma.
Because of the small number of patients, such studies necessarily group together all stages and sizes of tumors. As you might expect, most of the long-term survivors were in the group that had smaller tumors, clear margins on surgery, and less extensive disease.
The main determinant of survival with conventional treatment is the stage at which the tumor is first discovered. The optimal treatment would be surgery that both preserves anal continence but also guarantees prolonged survival. Unfortunately, because of the location and stage of the tumor, this is rarely possible.
CONVENTIONAL TREATMENTS: The choice of conventional treatment of anorectal cancer remains controversial. As with many other kinds of cancer, the debate centers around how "radical" the treatment needs to be, i.e. how much normal tissue has to be removed beyond the obviously diseased part.
For years, the standby operation consisted of a very radical procedure. This was an abdominoperineal resection (APR) with a dissection of both the pelvic lymph nodes and the groin lymph nodes on both sides (bilaterally).
APR involves the surgical removal of the anus and the lower part of the bowel. It is performed by cutting into the abdomen and the perineum (the space between the anus and the scrotum in men or the vulva in women). Next, an exterior opening (called a "stoma") is made, usually on the left side, through which fecal wastes can leave the body. The waste is collected in a special bag, which has to be periodically emptied. This procedure is known as a permanent colostomy.
For many years this was the standard treatment for rectal cancer. Happily, this situation is changing in a more conservative direction, and now patients with RECTAL cancer can frequently be treated conservatively with a combination of treatments that avoid the permanent colostomy.
But in America, at least, no such change away from the radical APR is standard in the treatment of anorectal melanoma. The biggest change was that, after many years, the bilateral groin dissection was declared to be unnecessary, and has now been dropped as a standard part of the treatment (Chiu, YS. Dis Colon Rectum 1980;23:122).
The debate continues, however. Doctors at Memorial Sloan-Kettering recently claimed that "those who had an APR were more likely to survive long term than those who did not." Since this was not a randomized controlled trial (RCT), however, it is difficult to know how comparable the two groups of patients were. (Patients may have been denied the APR precisely because their doctors thought they were too advanced to benefit from this surgery.)
Memorial Sloan-Kettering surgeons are generally found on the "radical" side of any treatment debate. Not surprisingly, MSKCC doctor M.S. Brady and colleagues reaffirmed that "APR should be considered in patients with localized anorectal melanoma, particularly those with smaller tumors and no evidence of nodal metastases" (Dis Colon Rectum 1995;38:146).
By contrast, doctors in the more conservative Department of Surgical Oncology, Roswell Park Cancer Institute, Buffalo, New York published a retrospective study in same year showing that patients who received local excision (LE) actually lived slightly longer than those getting APR: "The median survival of those with LE was 15.7 months and of those with APR 13.7 months" (J Surg Oncol 1995;58:118).
CONSERVATIVES ABROAD: In other countries there seems to be a trend towards more conservative treatments. A relatively big study in Holland found that sphincter-saving surgery was just as good as the very extensive APR procedure outlined above. (The sphincter in question is a ring of striated muscle fibers surrounding the anus, which controls the flow of feces from the body.) Sixteen patients were given this conservative operation while 18 patients received the radical operation. Doctor R.M. Roumen at the Sint Josephziekenhuis Veldhoven in The Netherlands reported, "We could not find a survival advantage for either one of these two treatment modalities."
While it was true that after the local procedure "far more local recurrences were seen" this fact did not influence the clinical course of these patients, "as they often rapidly succumbed to distant metastases." This hospital concluded that "in the future, patients presenting with an anorectal melanoma should be treated with a sphincter-saving surgical approach whenever possible."
In Mexico, similarly, the conclusion was that "the role of APR in maintaining local control over tumours larger than 4 cm or thicker than 5 mm remains elusive" (Surg Oncol 1996 Aug;5:165).
SEEK ADVICE: If you are confronting surgery for anorectal melanoma, my advice would be to always seek the most conservative surgery that is consistent with good medical practice. Of course, in this case, "good medical practice" is hard to define, when the medical community itself is so deeply divided. I urge you to seek out a second opinion with a conservative surgeon. (See further remarks below.)
ESGN: A potentially important development in the treatment of some cases of anorectal melanoma is the use of an artificial device called an ESGN that can be used to avoid permanent colostomy in some cases (Ann Surg 1996;224:702). ESGN stands for "electrically stimulated gracilis neosphincter." It can sometimes be incorporated as part of total anorectal reconstruction after excision of the rectum.
Doctor B.J. Mander and colleagues at the Academic Department of Surgery, St. Bartholomew's School of Medicine and Dentistry, Whitechapel, London, England, reported on the use of this device (which was invented for the treatment of a benign condition, called idiopathic fecal incontinence) in 12 patients with anal cancer, including anorectal melanoma. The procedure was deemed successful in eight patients. If you are facing a permanent colostomy, you might want to speak to your surgeon about this option.
CHEMOTHERAPY: Chemotherapy is infrequently used against anorectal melanoma. I do want to bring to your attention a 1997 study from the Department of Surgery, Sapporo Memorial Hospital of Surgery, Japan, reporting on the case of a 74-year-old woman with an anorectal melanoma. Surgery was performed but was "absolutely noncurative" because massive metastases in the pelvic and para-aortic lymph nodes.
However, after the surgery chemotherapy, composed of decarbazine (DTIC), vincristine (VCR), and nimustine hydrochloride (ACNU), achieved very good results. The patient, Dr. S. Nyui and colleagues report, has been well without any evidence of recurrence for more than three years (Surg Today 1997;27:753). ACNU is not approved for use in the United States. It is very similar, however, to the FDA-approved drugs carmustine (also called BCNU), lomustine (CCNU), etc. This raises the hope that in selected cases chemotherapy may be of real value in the treatment of anorectal melanoma. (See remarks below on how to choose best chemotherapy).
After this, as in all The Moss Reports there is a discussion of (a) clinics that provide alternative and complementary treatment for this and related tumors; and (b) treatments that can be done at-home. (Some of these may require the assistance of trained medical personnel.)