23. Anal Cancer - The GEC-ESTRO Handbook of Brachytherapy

Anal Cancer

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THE GEC ESTROHANDBOOKOF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 01/03/2023

TABLE 1 AJCC / UICC TNM 8TH EDITION

Tis T1 T2 T3

High-grade squamous intra-epithelial lesion Tumour ≤ 2cm in greatest dimension Tumour > 2cm but ≤ 5cm in greatest dimension

T

Tumour > 5cm in greatest dimension

Tumour of any size invading adjacent organs, for example vagina, urethra, or bladder. Note: direct invasion of the rectal wall, perirectal skin, subcutaneous tissue or the sphincter muscle is not classified as T4

T4

N

No regional lymph node metastasis

N1a N1b N1c

Metastases in inguinal, mesorectal, or internal iliac lymph nodes

N

Metastases in external iliac lymph nodes

Metastases in external iliac and any N1a lymph nodes

M0 M1

No distant metastasis Distant metastases

M

TABLE 2 ANAL CANCER STAGING (AJCC / UICC 8TH EDITION) Stage T

N

M

0

Tis T1 T2 T3 T1 T2 T4 T3 T4 Tx

N0 N0 N0 N0 N1 N1 N0 N1 N1 Nx

M0 M0 M0 M0 M0 M0 M0 M0 M0 M1

I

IIa IIb

IIIa

IIIb

IIIC

IV

similar or higher local control rates, disease-free survival rates and overall survival rates than EBRT [24–27], but no randomized controlled trials or systematic reviews have been performed to rigorously analyze the efficacy of IBT compared to EBRT.The choice of a brachytherapy boost is therefore more related to individual habits and local availability (for instance, brachytherapy is favored in France, but little used in the United States). IBT can be proposed for T1 and T2 tumours less than 5cm and involving no more than 50%, or even two thirds, of the anal canal circumference. The tumour should be clinically palpable. IBT can also be used for small T3 lesions which have responded well to chemoradiation. Some teams have emphasized the usefulness of a brachytherapy boost for Stage III tumours [17]. The overall treatment time (OTT) and the time gap between the end of the primary EBRT and the sequential boost are prognostic factors for the local control rate and should be as short as possible. Cordoba et al. [27] reported a significant superior LC when OTT was less than 58 days. Oblak et al. [28] showed that an OTT under 73 days was associated with superior 5-year LC (73% vs 56%). Deniaud-Alexandre et al. [29] reported a time gap less than 38 days as an independent favorable prognostic factor for DFS. Similar

results were obtained for Weber et al. [30] where 5-year LC was 84% when gap was less than 37 days and 61% otherwise.

Contraindications The contraindications to brachytherapy are of a general nature, e.g. contraindication to general or epidural anaesthesia or impossibility to be placed in a lithotomy position, but also specific to the oncological situation with a risk of failure andmajor toxicity from brachytherapy due to: - A tumour volume too large to treat: tumour involving more than two thirds of the anal canal circumference is a strict contraindication for brachytherapy because of the risk of long-termanal stenosis and decrease in internal anal sphincter function. The French protocol ACCORD-03 is even stricter and contraindicates brachytherapy if the circumferential involvement is more than 50% [31]. The tumour infiltration should also be limited, and the thickness of the lesion should not exceed 1cm. - Lack of response or tumour progression after chemoradiation (less than 50%of tumour regression): in such cases, the tumour should be considered radioresistant, and surgical resection