Anal Cancer Flashcards
Anal Cancer
In general, what is the standard treatment for anal canal squamous cell cancers?
concurrent chemoradiation (5-FU + MMC)
Anal Cancer
Which is/are TRUE regarding anal canal anatomy?
I. The anal canal is 7 to 8 cm in length.
II. The posterior wall of the anal canal is longer than the anterior.
III. The canal ends superiorly at the palpable upper border of the anal sphincter and puborectalis muscle of the anorectal ring.
IV. The distal end at the anal
verge is the level at which the walls of the anal canal come in contact in their normal resting state; it approximates the palpable groove between the lower edge
of the external sphincter and the subcutaneous part of the anal verge and
the junction with true skin.
II and III.
***
I. 3-4
II. lower edge of internal sphincter and the subcutaneous part of the external sphincter.
Anal Cancer
Perianal carcinomas are arbitrarily
considered to be cancers arising from the skin within a ___-cm radius of the anal
verge.
5 cm
Anal Cancer
Which is FALSE regarding anal canal histology?
I. The perianal skin is similar to hair-bearing skin elsewhere.
II. At the anal verge, the skin
blends with a pale-colored zone, sometimes called the pecten, lined by modified cuboidal epithelium that lacks hair or glandular structures. This zone merges just below the dentate or pectinate line, which marks the mucosal folds
of the anal valves, with a transitional epithelium that incorporates features of
rectal, urothelial, and squamous epithelium.
III. The purplish red–colored
transitional zone extends proximally for about 2 cm until the pinker glandular mucosa of the rectum becomes dominant.
II.
pecten is lined by modified squamous epithelium (not cuboidal)
Anal Cancer
Lymphatic drainage of the perianal skin, anal verge, and canal distal to the dentate line.
superficial inguinal
with communication to the femoral and external iliac
Anal Cancer
Lymphatic drainage of the anal canal around and above the dentate line?
internal pudendal
hypogastric
obturator nodes
(internal iliac system)
Anal Cancer
Lymphatic drainage of the proximal anal canal?
perirectal
superior hemorrhoidal nodes
(inferior mesenteric system)
Anal Cancer
Nerve supply of the smooth muscles of the internal sphincter
sympathetic fibers of S2-4 and hypogastric plexus
Anorectal continence is mediated by both cerebrospinal nerves and the
autonomic system. The smooth muscle of the internal sphincter is supplied by
parasympathetic fibers from the second, third, and fourth sacral segments as well
as sympathetic fibers from the hypogastric plexus. The upper canal has selective
sensitivity for intraluminal differences in pressure, and the autonomic nerves
mediate both the inhibitor and facilitator reflexes of the internal sphincter.
Anal Cancer
Nerve supply of the striated muscles of the external sphincter
internal rectal nerve, (a branch of the pudendal nerve arising from S2-4).
***
The
striated muscle of the external sphincter is under voluntary control and
innervated by the internal rectal nerve, a branch of the pudendal nerve arising
from the second, third, and fourth sacral nerves. The internal rectal nerve also
transmits pain, touch, and other sensations from the anal lining below the dentate
line and from the perianal skin
Anal Cancer
What is the most common histologic classification of anal cancers?
SCC
Anal Cancer
Adenocarcinomas from the rectal-type mucosa in
the upper canal are classified as primary anal cancers, as long as they are within the anatomic boundaries of the anal canal.
TRUE or FALSE
FALSE.
Adenocarcinomas from the rectal-type mucosa in
the upper canal are classified as primary rectal cancers.
Anal Cancer
What HPV subtype/s is/are most commonly associated with the development of anal cancer?
HPV-16.
Subtypes of HPV with a high risk of association with cancer are type 16 in particular and, to a lesser extent, types 18, 31, 33, 35, and others
Anal Cancer
In general, what are the risk factors for developing anal cancer?
sexually transmissible viruses (HPV)
,
immunosuppression (HIV and transplant, etc),
tobacco smoking
Anal Cancer
Anal cancer is considered an AIDS-defining illness.
TRUE or FALSE?
False.
***
However, although anal cancer has not been designated an acquired immunodeficiency
syndrome (AIDS)-defining condition, data from the U.S. AIDS Cancer Registry
linkage study showed that the rate of HPV-associated cancers and precursors was
increased in HIV-infected persons for all anogenital sites compared with the
general population.
Anal Cancer
HAART introduction decreased the rates of anal cancer development in HIV-infected individuals.
TRUE or FALSE?
FALSE.
***
Although there was a
decrease in the incidence of Kaposi sarcoma and lymphoma by a few years after HAART became available, at the time of the review, there had been no
significant reduction in the incidence of less common malignancies such as
anogenital cancers.
Anal Cancer
Benign conditions causing chronic and constant inflammation of the anal mucosa such as fistulae, fissures, and hemorrhoids are considered as risks factors predisposing to anal cancer.
TRUE or FALSE?
Benign conditions such as fistulae, fissures, and hemorrhoids do not appear to predispose to cancer.
Chronic anal inflammation due to inflammatory bowel disease has also been discounted as a risk factor.
Anal Cancer
Which is/are TRUE regarding AIN?
I. Most squamous cell cancers of the anal region, especially the canal, are believed
to be preceded by high-grade AIN.
II. It has been estimated that no more
than 1% of cases with AIN develop invasive cancer per year.
III. Anal dysplasia recurs
frequently despite excision, laser ablation, or topical therapies.
none I only II only III only I & II only I & III only II & III only
All.
Anal Cancer
What are the two most common mechanism of spread in anal cancers?
direct extension
lymphatic extension
Anal Cancer
Anal cancer invades the prostate gland more commonly than the vaginal septum.
TRUE or FALSE?
False.
***
Invasion of the vaginal septum and vaginal mucosa is more common than
invasion of the prostate gland, but anovaginal fistulas occur in fewer than 5% of
women.
Anal Cancer
What is the most common pattern of relapse?
locoregional failure (in the area of the primary tumor and lymph nodes)
Anal Cancer
Perianal cancers tend to grow locally and may extend into the anal canal.
When the site of origin is in doubt, it is conventional to classify the cancer as
arising in the anal canal.
TRUE or FALSE?
True.
Anal Cancer
Where is the most common site of metastasis in perianal cancers?
ipsilateral inguinal nodes.
***
The ipsilateral inguinal nodes are the most common site
of metastasis and are involved in from 5% to 20% of cases. Extrapelvic
metastases are uncommon except in locally advanced cancer or those with nodal
metastases.
Anal Cancer
What is the most common presenting symptoms?
Bleeding and anal discomfort are the most common symptoms and are reported by about half the patients.
Less common complaints include awareness of an anal mass, pruritus, and anal discharge.
Anal Cancer
What imaging modality is considered the most accurate method for assessing the primary cancer “including” the pelvic nodes.
MRI
Anal Cancer
Anal Canal TNM staging
Identify the T-stage:
Tumor less than 2 cm but with invasion to vagina, urethra, bladder
T4
Anal Cancer
Anal Canal TNM staging
Identify the T-stage:
Tumor less than 2 cm but with invasion to rectal wall, perirectal skim, subcutaneous tissue, or sphincter muscle.
T1
***
T1 is 2 cm or less.
(invasion
of the rectal wall, perirectal skin, subcutaneous tissue, or sphincter muscle is not
included as T4).
Anal Cancer
Anal Canal TNM staging
Identify the T-stage:
Bowen disease
Tis
***
High-grade squamous intraepithelial lesion (previously termed carcinoma in situ, Bowen disease, AIN II–III, high-grade AIN)
Anal Cancer
Anal Canal TNM staging
Identify the T-stage:
3 cm
T2 *** >2 cm but ≤5 cm *** >5 cm is T3
