Anal cancer Flashcards by Sam O'Boy

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

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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

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What proportion of cancers are node positive at presentation

12% are node positive at presentation

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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

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What proportion of AIN progresses to anal cancer after 5yrs

10%

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How does anal cancer tend to present

Bleeding, pain, itching, discharge
Faecal incontinence and frequency
Palpable mass in <25% of pts

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Does HPV predict for response to CRT

No - carry worse prognosis (opposite to H&N)

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What are the negative prognostic factors for anal cancer

Increasing stage
Size (>5cm)
Nodal involvement
Mets

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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

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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

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When is a PET scan indicated for investigation of anal cancer

> T2 stage

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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

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What are the aims of treatment of anal cancer

Achieve cure with locoregional control
Preservation of anal sphincter function
QOL

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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

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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

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When is CRT standard of care for anal cancer

Anal canal tumour
Anal margin tumours >1cm

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What category treatments are anal SCC

Cat 1

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When is a defunctioning stoma indicated for anal cancer

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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

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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

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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?

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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

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GFR <50 - risk of thrombocytopenia

For chemoRT, what chemotherapy dose is given if elderly / poor PS

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Mitomycin C, at dose 8mg/m2
AND 5FU at 750mg/m2

What are the indications for adjuvant CRT for anal cancer

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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%

Anal cancer Flashcards

(44 cards)