Anal cancer Flashcards
How are anal cancers categorised anatomically
Anal canal - majority.
Anal verge - Lower end of anal canal
Anal margin - 5cm of perianal skin, to lower limit of anal canal
What is the lymphatic drainage of anal tumours
Low tumours of the anal margin and verge drain to the peri rectal nodes, inguinal & femoral nodes, iliac and para-aortic
Mid and upper tumours drain to internal pudendal nodes, obturator, pre-sacral and internal iliac nodes
What proportion of cancers are node positive at presentation
12% are node positive at presentation
What are the risk factors for anal cancer
HPV - 16 & 18
Multiple sexual partners, ano-receptive intercourse
Cervical CIN & cancer, vaginal/vulval VIN & SCC
Smoking
Immunosuppression & HIV
What proportion of AIN progresses to anal cancer after 5yrs
10%
How does anal cancer tend to present
Bleeding, pain, itching, discharge
Faecal incontinence and frequency
Palpable mass in <25% of pts
Does HPV predict for response to CRT
No - carry worse prognosis (opposite to H&N)
What are the negative prognostic factors for anal cancer
Increasing stage
Size (>5cm)
Nodal involvement
Mets
How is anal cancer investigated
History and examination incl genital examination and EUA
Speculum examination to assess vulva/vagina/cervix
Assess for presence of fistula (and consider defunctioning stoma)
FNA of positive nodes
Imaging - MRI pelvis
PET if >T2
What should an MRI comment on for a potential anal cancer
Relationship between inferior aspect of tumour and anal margin
Depth of invasion
Length and quadrant of involvement
Evidence of adjacent organ involvement
When is a PET scan indicated for investigation of anal cancer
> T2 stage
How is nodal disease defined for anal cancer
N1a - internal iliac, mesorectal or inguinal nodal involvement only
N1b - external iliac node involvement only
N1c - external iliac node AND mesorectal / inguinal / int iliac nodal involvement
What are the aims of treatment of anal cancer
Achieve cure with locoregional control
Preservation of anal sphincter function
QOL
When is local excision indicated for anal cancer
Anal margin tumours - <1cm, well differentiated, and if macroscopically clear margins are possible (>5-10mm) without sphincter damage, to allow histological clear margin of >1mm
If tumour >1cm -> primary CRT
Surgery contraindicated for anal canal tumours
When is an APER indicated for anal cancer
What doesn’t an APER treat
APER indicated if radical CRT is contraindicated:
-Prev RT
- adenocarcinoma or adenosquamous carcinoma histology (less likely to respond to CRT)
- transplated kidney in pelvis
- IBD
- wish to preserve fertility
Doesn’t treat pelvic LNs
When is CRT standard of care for anal cancer
Anal canal tumour
Anal margin tumours >1cm
What category treatments are anal SCC
Cat 1
When is a defunctioning stoma indicated for anal cancer
Bulky tumours - Obstruction
Faecal incontinence
Risk of fistulation
Significant pain
What is the RT dose, for a T1-2 N0 tumour and what stage is this
T1-2 N0 (stage I-IIA): 50.4Gy/28# with 40Gy/28# electively to pelvic nodes
What is the RT dose, for a T3-4 N0 tumour, or any node positive tumour
and what stage is this
Dose to primary tumour (and nodes >3cm) - 53.2Gy/28#
Dose to positive nodes - 50.4Gy/28#
Dose to elective nodal volume - 40Gy/28#
T3N0 = stage IIB
node positive = IIIA and above
What chemotherapy regimen is given alongside anal RT?
Concurrent chemotherapy
Mitomycin C + capecitabine is SOC
MMC given IV day 1 - 12mg/m2, to max dose 20mg
capecitabine 825mg/m2 bd, on days of RT (M-F) only
Can give 5FU instead of cape - days 1-4 & 29-32 ie wks 1&5 - 1000mg/m2 over 24hrs via pump
MMC only given if GFR >50
When is mitomycin C omitted
GFR <50 - risk of thrombocytopenia
For chemoRT, what chemotherapy dose is given if elderly / poor PS
Mitomycin C, at dose 8mg/m2
AND 5FU at 750mg/m2
What are the indications for adjuvant CRT for anal cancer
Positive margins (<1mm) and further surgery not possible
Where completeness of excision cannot be guaranteed
Those at risk of pelvic nodal involvement
What is the adjuvant dose for anal CRT?
41.4Gy/23# - scar + margin, with MMC + capecitabine
30Gy/15# - scar + margin, with MMC+5FU for wk1 only
What volumes are margins are used for a T1 anal tumour treated with primary CRT
GTV - Gross primary anal tumour
CTV - GTV + 1cm
Cover Anal canal, verge, internal and external anal sphincters.
Edit from bone & muscle.
PTV - CTV + 1cm
What volumes are margins are used for a T2N0 anal tumour treated with primary CRT
GTV-P
CTV - GTV +1cm
Cover Anal canal, verge, internal and external anal sphincters.
Elective nodal volume - inguinal, femoral, int & ext iliac, obturator, pre-sacral
Start 2cm above SI-joint or 1.5cm above GTV
If node negative, include lower 5cm of mesorectum
If node positive, include whole mesorectum in CTV
PTV = CTV +0.5cm (for tumour volume) and +1cm (for elective volume)
What volumes and margins are used for a large T2, or T3-4 or node positive anal tumour treated with primary CRT
GTV-P
CTV-P = GTV +1.5cm
Cover Anal canal, verge, internal and external anal sphincters.
PTV = CTV +1cm (for tumour volume)
GTV-N
CTV-N = GTV-N +0.5cm
Elective nodal volume - inguinal, femoral, int & ext iliac, obturator, pre-sacral
Start 2cm above SI-joint or 1.5cm above GTV
If node negative, include lower 5cm of mesorectum
If node positive, include whole mesorectum in CTV
PTV-N = CTV +0.5cm (GTV-N & elective nodal volume)
What OARs would be planned for anal CRT
Bladder, rectum and small bowel, perineum & genitalia, femoral heads
What is the follow up after completion of primary CRT for anal cancer
6mth MRI
What is the local recurrence rate after primary CRT
20%, typically within first 18mths
How is recurrent disease managed after primary CRT
Workup of recurrence: Biopsy, MRI, PET-CT to exclude distant mets
Local recurrence within RT volume - salvage surgery (APER / exenteration), or if not suitable for surgery / sufficient interval, reirradiation
Para-aortic LN - SABR
Isolated Inguinal node - surgery (block dissection)
What is the first line management of metastatic anal SCC?
Based on what trial
What is the prognosis for this regimen
Carboplatin/paclitaxel
InterAAct phase II study (carbo/taxol vs cisplatin/5FU)
mOS 20mths
How can CRT be used in the palliative setting
30Gy in 15# over 3 weeks
Primary & Nodes + 3 cm margin
Concurrent 5FU week 1 only
What must be included in RT volume if tumour extends into the rectum
all of the mesorectum in elective volume
where does anal cancer tend to metastasise to
Liver, very rarely brain
What numbers are important for anal cancer T staging
And for N staging
2, 5
t1 = ≤2cm
T2 = 2-5
t3 = >5cm
t4 = local inasion (not sphincters)
N1a - inguinal, mesorectal, int iliac
N1b - ext iliac
N1c - both
when does staging change management for an anal cancer CRT
stage IIA and below ie T1-2N0, treat with lower dose RT (50.4/28 & 40/28 to elective volume)
stage IIB and above (T3N0 or node positive) - treat with higher dose RT - 53.2/28 and 40/28 to elective volume
what margin is needed for surgery
> 1mm
If ≤1mm, given adjuvant CRT
For an early anal cancer, what is the GTV, GTV-CTV margin, CTV, and CTV-PTV margin
What else is included for a larger tumour (>4cm)
GTV - gross tumour
GTV-CTV margin 1cm
CTV - GTV +1cm, also including anal canal, verge, int & ext sphincters, edited off bone and muscle
CTV-PTV margin - 1cm
T1N0 - tumour only, no elective nodal volume
T2N0 - include elective nodal volume, starting 2cm above SI joints, with.
CTVe-PTV margin of 0.5cm
For an advanced anal cancer, what is the GTV, GTV-CTV margin, CTV, and CTV-PTV margin
For T3+ or node positive:
GTv-CTVp margin now 1.5cm, also including anal canal, verge, int & ext sphincters, edited off bone and muscle
CTV-PTV margin - 0.5cm
elective nodal volume, starting 2cm above SI joints
GTV-N -> CTV-N 0.5cm
CTV-PTV margin - 0.5cm
When would surgery (APER, not local excision) be considered for anal cancer
Prev pelvic EBRT
Transplanted kidney in the pelvis & early disease
To preserve fertility
IBD - radiosensitivity
what is the outcome after radical chemoRT
Local control 60%, 5yr survival 30-60%
What is the response rate to primary CRT for anal SCC
Complete tumour regression in 80-90%
