RT Book, Section
A1 Ursem, Carling
A1 McQuaid, Kenneth R.
A2 Papadakis, Maxine A.
A2 McPhee, Stephen J.
A2 Rabow, Michael W.
A2 McQuaid, Kenneth R.
SR Print(0)
ID 1184389875
T1 Carcinoma of the Anus
T2 Current Medical Diagnosis & Treatment 2022
YR 2022
FD 2022
PB McGraw-Hill Education
PP New York, NY
SN 9781264269389
LK accessmedicine.mhmedical.com/content.aspx?aid=1184389875
RD 2024/04/25
AB The  anal  canal  is  lined  from  its  proximal  to  distal  extent  by  columnar,  transitional,  and  non-keratinized  squamous  epithelium,  which  merges  at  the  anal  verge  with  the  keratinized  perianal  skin.  Cancers  arising  from  the  mucosa  of  the  anal  canal  are  relatively  rare,  comprising  only  1–2%  of  all  cancers  of  the  anus  and  large  intestine.  Squamous  cancers  make  up  the  majority  of  anal  cancers.  Anal  cancer  is  increased  among  people  practicing  receptive  anal  intercourse  and  those  with  a  history  of  anorectal  warts.  In  over  80%  of  cases,  HPV  may  be  detected,  suggesting  that  this  virus  is  a  major  causal  factor.  In  a  large  controlled  trial,  HPV  vaccination  of  healthy  men  (16  to  26  years  old)  who  have  sex  with  men  decreased  the  incidence  of  anal  intraepithelial  neoplasia  by  50%.  Women  with  anal  cancer  are  at  increased  risk  for  cervical  cancer  (which  may  be  due  to  a  field  effect  of  oncogenic  HPV  infection)  and  require  gynecologic  screening  and  monitoring.  Anal  cancer  is  increased  in  HIV-infected  individuals,  possibly  due  to  interaction  with  HPV.  Nine-valent  HPV  (9vHPV)  vaccine  is  recommended  for  boys  and  girls  starting  at  age  11  or  12  and  for  individuals  up  to  age  26  who  have  not  been  previously  vaccinated.  Thereafter,  shared  clinical  decision-making  regarding  HPV  vaccination  is  recommended  for  some  adults  aged  27  through  45  years  who  are  not  adequately  vaccinated.