Anal carcinomas are an uncommon group of heterogeneous lesions that
have represented a therapeutic enigma for many years. The mere rarity of
these cancers alone has proven to be a major impediment to the formulation
of a standardized approach to treatment planning.
Much of our current knowledge about the natural history and the biology
of these tumors derives from small, single-institution, retrospective reviews
of questionable scientific merit that extended over long periods and lacked
appropriate control groups or utilized historical controls. These data
have been further criticized due to the anatomic definition of the components
of the anal canal and anal margin and the nonstandardization of the staging
systems used until the American Joint Committee on Cancer (AJCC) and International
Union Against Cancer (UICC) systems became widely accepted after 1987.[1,2]
In addition, treatment modalities for anal cancer have varied with individual
institutional experience and bias. Compounding this even further, there
has been variation even within individual institutions in terms of the
chemotherapy regimens utilized, methods of delivering radiation therapy
(interstitial implant vs external beam), and whether a single modality
or combined approach was employed. Important therapeutic end points, such
as disease-free survival and site of first failure, have also been glaringly
omitted from many of these published series.
Collectively, the nonuniformity of the existing data prevents them from
being subjected to meaningful statistical evaluation. The article by Drs.
Mendenhall, Copeland, and associates of their institutional experience
and their review of the literature, published in the December issue of
ONCOLOGY (10:1843-1854, 1996), addresses some of these important issues
and stands as a commendable attempt to formulate a structured approach
to the treatment of this rare entity.
It is clear that the management of this disease represents another example
of the necessity for a multimodality approach to solid tumors. This approach
mandates consultation among surgeons, medical oncologists, and radiation
oncologists to formulate the therapeutic strategy that ensures the best
outcome, measured not only by disease-free and overall survival but also,
importantly, by functional preservation.
The primary goals of treatment have evolved to include not only local
control and improved survival but also preservation of normal anal function.
Although an abdominoperineal resection was the preferred approach in the
past, with time, it has become well accepted that perianal lesions are
not as invasive and do not metastasize to regional lymph nodes as frequently
as their anal canal counterparts, and therefore, do not necessitate
this radical treatment.
Many series have subsequently reported on the feasibility of local excision
for early-stage, small tumors that do not demonstrate invasion of the surrounding,
deeper tissue. In a previous institutional review of 16 patients treated
for perianal squamous cell carcinomas by Schraut et al at The University
of Chicago, the concept of local excision for treatment of the tumors was
supported by a 67% absolute 10-year survival. This paralleled the experience
of Papillon et al, who, in a 1992 review of epidermoid carcinoma of the
anal margin, clearly demonstrated the benefit of local excision in controlling
the disease and concomitantly preserving sphincter function. Local recurrences
were generally controlled by repeat excision or by the more radical abdominoperineal
resection. Abdominoperineal resection was used successfully in 3 of 10
patients in the series of Cutuli et al and in 2 of 8 patients in the
Cleveland Clinic series.
A number of conclusions can be drawn from a review of the literature,
such as that provided by Mendenhall et al. These conclusions agree with
our own experience. We concur with Mendenhall et al that early T1 and T2
lesions may be treated with either local excision with clear margins or
radiotherapy. One can accept the relatively high local recurrence rate
with these approaches since the recurrences tend to be amenable to further
excision, radiotherapy, or abdominoperineal resection for cure.
Stage T2 and more advanced lesions should be considered for prophylactic
groin irradiation due to the significant likelihood of regional nodal disease.
In their series of 57 patients, Papillon et al found a high incidence of
inguinal lymph node recurrence in those individuals with T2-T3, N0 tumors.
This was their rationale for elective bilateral inguinal irradiation at
the time of treatment of the primary lesion. Other investigators, such
as Cutuli's group, found no inguinal recurrences in patients with N0 tumors
who received prophylactic groin irradiation. In all of these series,
there was minimal treatment-associated morbidity. Taking these data into
consideration, it seems reasonable that, in patients with T2 or more advanced
lesions, groin irradiation be instituted at the time of treatment of the
primary cancer. It is unclear at present whether this therapy achieves
statistically improved disease-free or long-term survival.
More advanced T3 and T4 cancers are best treated with the combination
of cytotoxic chemotherapy and radiation therapy, with abdominoperineal
resection reserved for patients with poor sphincter function (manifested
by fecal incontinence) and for those fortunate individuals who experience
a significant clinical response with downstaging of their tumors to allow
for consideration of potentially curative surgery. There does not appear
to be any role for prophylactic regional lymph node dissection.
Role of Lymph Node Dissection
The role of either hypogastric lymph node/extended pelvic lymph node
dissection or radical groin dissection has been a topic of debate for many
years. According to our institutional experience and the experience of
other surgeons, perianal squamous cell carcinoma rarely metastasizes to
pelvic lymph nodes, and thus, does not warrant routine dissection. Inguinal
node involvement--a well accepted, poor prognostic factor--occurs with
relatively high frequency in patients with more advanced tumors. However,
since radical groin dissection is attended by considerable morbidity and
severe disability, it is difficult to justify a prophylactic dissection
on theoretical grounds alone. Inguinal lmph node dissection is still used
for local control of nodal disease.
Importance of Follow-up
Lastly, one important, seemingly obvious point in the management of
cancers of the anal margin is the need for careful, close interval follow-up
by examination and proctoscopy for early detection of local or nodal recurrences.
Given the sometimes indolent pattern of these tumors, such follow-up should
be continued for at least 10 years.
1. American Joint Committee on Cancer: Manual For Staging of Cancer,
3rd ed. Philadelphia, JB Lippincott, 1987.
2. Hermanek P, Sobin LH: TNM Classification of Malignant Tumors, 4th
ed. New York, Springer Verlag, 1987.
3. Beahrs OH, Wilson SM: Carcinoma of the anus. Ann Surg 184:422-428,
4. Schraut WH, Wang CH, Dawson PJ, et al: Depth of invasion, location,
and size of cancer of the anus dictate operative treatment. Cancer 51:1291-1296,
5. Papillon J, Chassard JL: Respective roles of radiotherapy and surgery
in the management of epidermoid carcinoma of the anal margin. Dis Colon
Rectum 35:422-429, 1992.
6. Cutuli B, Fenton J, Labib A, et al: Anal margin carcinoma: 21 Cases
treated at the Institute Curie by exclusive curative radiotherapy. Radiother
Oncol 11:1-6, 1988.
7. Al-Jurf AS, Tumbull RB, Fazio VW: Local treatment of squamous cell
carcinoma of the anus. Surg Gynecol Obstet 148:576-578, 1979.