A_rectal

AP portal of patient with T4 rectal cancer. B: Lateral portal of a patient with T4 rectal cancer.

Inferior The minimum would be at least a 4 cm margin from the inferior extent of the cancer or the anal verge for tumors within 2-3 cm of the anal verge, as identified by a merker on simulation.
Superior L5/S1 juntion
Lateral 2 cm lateral to the bony pelvis or on nodes > 1.5 cm taken at its widest point
Anterior This will cover the internal iliac, presacral lymph nodes and at least 3 cm margin on the anterior rectal wall/tumor for T3 lesions. For T4 lesions the external iliac nodes should be included with a field border 1 cm anterior to the symphysis pubis.
Boost field A 2-3 cm margin around the rectal tumor and any lymph nodes > 1.5 cm as identified on pre-treatment evaluation, but must include the whole of the sacral hollow. Exclusion with custom blocking of as much of small bowel as possible is recommended

Inferior The minimum would be at least a 4 cm margin from the inferior extent of the cancer or the anal verge for tumors within 2-3 cm of the anal verge, as identified by a marker on simulation.
Superior L5/S1 juntion
Lateral 2 cm lateral to the bony pelvis or on nodes > 1.5 cm taken at its widest point
Anterior This will cover the internal iliac, presacral lymph nodes and at least 3 cm margin on the anterior rectal wall/tumor for T3 lesions. For T4 lesions the external iliac nodes should be included with a field border 1 cm anterior to the symphysis pubis.
Boost field A 2-3 cm margin around the rectal tumor and any lymph nodes > 1.5 cm as identified on pre-treatment evaluation, but must include the whole of the sacral hollow. Exclusion with custom blocking of as much of small bowel as possible is recommended

Inferior The minimum would be at least a 4 cm margin from the inferior extent of the cancer or the anal verge for tumors within 2-3 cm of the anal verge, as identified by a merker on simulation.
Superior L5/S1 juntion
Lateral 2 cm lateral to the bony pelvis or on nodes > 1.5 cm taken at its widest point
Anterior This will cover the internal iliac, presacral lymph nodes and at least 3 cm margin on the anterior rectal wall/tumor for T3 lesions. For T4 lesions the external iliac nodes should be included with a field border 1 cm anterior to the symphysis pubis.
Boost field A 2-3 cm margin around the rectal tumor and any lymph nodes > 1.5 cm as identified on pre-treatment evaluation, but must include the whole of the sacral hollow. Exclusion with custom blocking of as much of small bowel as possible is recommended

Inferior The minimum would be at least a 4 cm margin from the inferior extent of the cancer or the anal verge for tumors within 2-3 cm of the anal verge, as identified by a merker on simulation.
Superior L5/S1 juntion
Lateral 2 cm lateral to the bony pelvis or on nodes > 1.5 cm taken at its widest point
Anterior This will cover the internal iliac, presacral lymph nodes and at least 3 cm margin on the anterior rectal wall/tumor for T3 lesions. For T4 lesions the external iliac nodes should be included with a field border 1 cm anterior to the symphysis pubis.
Boost field A 2-3 cm margin around the rectal tumor and any lymph nodes > 1.5 cm as identified on pre-treatment evaluation, but must include the whole of the sacral hollow. Exclusion with custom blocking of as much of small bowel as possible is recommended

The rectum begins at S3 and is appx. 15 cm long.

The T staging for rectal cancer is based on the depth of invasion:

Tis: CIS or invasion into lamina propria
T1 (submucosa)
T2 (muscularis propria)
T3 (through muscularis and into perirectal tissues)
T4a (surface of visceral peritoneum)
T4b (adjacent organs involved)

In the 7th edition of AJCC, N1 and N2 is further broken down into:
N1a: mets to 1 regional LN; N1b: mets to 2-3 regional LN; N1c: tumor deposits in subserosa, mesentery, or non-peritonealized pericolic or perirectal tissues without regional LN mets.
N2a: mets to 4-6 LN; N2b: mets to >=7 LN.

Carcinoembryonic antigen (CEA) is routinely ordered for patients with colorectal cancer b/c it may help monitor response to therapy and disease progression.

In general, T1-2N0 rectal cancer patients can get upfront surgery +/- adjuvant CRT, whereas T3-4 or N1 patients should receive neoadjuvant CRT followed by surgery and adjuvant 5-FU/LV or FOLFOX.

The criteria for local excision alone in rectal cancer include T1 lesion, ≤3 cm tumor that is superficial (<3 mm submucosal depth), lesion involving ≤1/3 of rectal circumference, N0 by EUS or MRI, low grade tumor/no LVI, reliable patient.

Adjuvant CRT should be administered to patients with a poor risk T1 lesion after local excision that are poorly differentiated, with bad histologies, margins < 3mm, >3cm size, and +LVSI, and all T2 cancer after local excision, and for all T3/4 or N+ cancers after LAR or APR.

The historic LR rate for T3-4 or N1 rectal cancer is approx. 25%. This is improved with better surgery (i.e. TME, LR 11% (Dutch TME study)).

Normal anatomy of the mesorectum. (a) Axial turbo spin-echo T2-weighted MR image shows the mesorectal fascia as a thin, hypointense layer (white arrowheads) surrounding hyperintense mesorectal fat. On the anterior aspect, the mesorectal fascia appears more thickened and is difficult to differentiate from the Denonvillier fascia (black arrowheads).

Rectum is surrounded by mesorectal fat within the mesorectal fascia (red arrows).
P: prostate and V: seminal vesicles.

5-FU (225 mg/m2) is given concurrently with RT via continuous infusion as NCCTG 86-47-51/Intergroup trial (O’Connell MJ et al., NEJM 1994) showed improved 4 yr OS when compared to bolus administration in the adjuvant CRT setting (70% vs. 60%).

Both the Dutch and Swedish rectal cancer studies used neoadjuvant RT in 25 Gy in 5 fxs (5 Gy x 5). Patients typically underwent surgical resection within one week of RT completion. of note, Swedish was the only rectal trial showing a survival benefit. The Swedish trial did not use TME wheras the Dutch one did.

The German Rectal Cancer Trial (Sauer R et al., NEJM 2004) compared pre-op to post-op CRT in T3/4 or N+ rectal cancer (RT was to 50.4 Gy for NA arm and 55.8 Gy for post-op arm with 5FU chemo (CI 5FU days 1-5 @ 1000mg/d, wk 1 and 5) and found a similar 5 yr OS and DFS, but better LR rates (6% vs. 13%), fewer acute (27% vs. 40%) and late toxicities (14% vs. 24%), and better sphincter-preservation rates (39% vs. 19%) in the pre-op CRT arm. Most of the acute and late toxicities were especially d/t acute/chronic diarrhea and anastomatic stricture.

According to the German Rectal Cancer Trial., the pCR rate is 8%.

The sphincter-preservation rate in the NA CRT arm in the German Rectal Cancer Study (Sauer R et al., NEJM 2004) was 39% at 5 yrs (compared to 19% in the postoperative CRT arm).

One should wait appx. 6-8 weeks after NA CRT for rectal cancer until surgery is performed to allow for adequate downstaging.

All patients in the German Rectal Cancer Study (Sauer R et al., NEJM 2004) received 4-5 cycles of bolus 5-FU after either surgery (NA CRT arm) or CRT (adjuvant arm).

Rectal cancer patients should undergo CT simulation in the prone position, on a belly board, with a full bladder (optional placement of anal/vaginal markers and/or rectal contrast).

For rectal cancer, the tumor/bed (+2-5 cm margin), presacral and internal iliac nodes should be included in the RT fields.

The external iliac nodes need to be encompassed for T4 rectal lesions.

Whole pelvis fields (3 fields) with a PA field and two opposed lateral fields are typically employed for rectal cancer.

The RT doses for rectal cancer are as follows:
NA/Post-op: Initial WP (3-fld) to 45 Gy in 1.8 Gy/fx, CD to tumor/bed +2-3 cm (opposed laterals only, or 3-D conformal RT) to 50.4 Gy or 54 Gy if small bowel out of the way
Definitive/unresectable: Initial to 45 Gy, CD1 to 50.4 Gy, consider CD2 with conformal RT to 54-60.4 Gy if small bowel limited.

The anatomic boundaries for the RT fields in rectal cancer are as follows:
PA: superior at L5-S1, inferior at bottom of ischial tuberosity or 3 cm below tumor volume, lateral at 1.5 cm from pelvic inlet
Laterals: 1 cm posterior behind the entire bony sacrum, anterior behind pubic symphisis for T3 (infront if T4), superior/inferior same as PA. Blocks applied to spare small bowel.

The posterior border on the lateral fields usually stays the same (behind bony sacrum) for the CD portion of the RT for rectal cancer given the high rate of local recurrence in this region.

Inraoperative RT (IORT) should be considered in rectal cancer for close/+ margins or as an additional boost, especially with T4 tumors or with recurrent tumors. The typical dose is 10-15 Gy to the 90% IDL.

Bolus administration of 5-FU confers greater hematological toxicity, whereas continuous infusion confers greater GI toxicity (Smalley SR et al., JCO 2006).

Small bowel obstruction was more likely in the NA RT arm in the Swedish Rectal Cancer Trial (RR 2.5), (Birgisson H et al., Br J Surg 2008). Maybe a limitation of hypofractionated regimen (5 Gy x 5)

The small bowel dose should be limited to 45 Gy in the treatment of rectal cancer.

Signs and symptoms can occur as early as 6
–18 months following RT. Frequent symptoms include (bloody) diarrhea, colicky abdominal pain, and N/V. Less common: SBO, fistulas, bowel perforation and severe bleeding. Bowel malabsorption with weight loss. Damage of ileum can impair resorption of vitamin B12 and bile acid with steatorrhoea as a consequence. (Guckenberger et al. Int. J Colorectal Dis 2006).

Make sure the perineal wound is included in the fields.

IORT should be considered for a close or positive margin, especially for patients with T4 or recurrent cancers. If IORT is not available, 10-20 Gy EBRT could be considered soon after surgery, prior to adjuvant chemotherapy.

after non-TME: 25% LR
after TME: LR=11%
TME with NA chemo/rt in Dutch study (5Gyx5) showed LR improved from 11% to 6% with addition of CRT

LVSI, T2, piecemeal resection, colloid, signet ring, poorly differentiated

Sphincter preservation was 39% (vs. 19%) in German trial, so I’d think 20% (the absolute difference is a decent answer). Perez says 60% with CMT, 45% with RT alone, but I think this is for all comers.

Adenocarcinoma: No
SCC: Yes

Indications to treat
T4
Bowel perforation
Note: LN disease is not strongly supported at UF as a colon cancer postop RT indication

Close the patient up. Then do preop RT (+/- CTX) to 45-50.4 Gy. Take the patient back to OR 4 weeks after for another attempt.

Radiation therapy fields should include the tumor or tumor bed, with a 2-5 cm margin, the presacral nodes, and the internal iliac nodes. The
external iliac nodes should also be included for T4 tumors involving anterior structures.
Multiple radiation therapy fields should be used (generally a 3 or 4 field technique). Positioning and other techniques to minimize the volume
of small bowel in the fields should be encouraged.

Intraoperative radiotherapy (IORT), if available, should be considered for very close or positive margins after resection, as an additional
boost, especially for patients with T4 or recurrent cancers. If IORT is not available, 10-20 Gy external beam radiation and/or brachytherapy to
a limited volume could be considered soon after surgery, prior to adjuvant chemotherapy.

Female patients should be considered for vaginal dilators and instructed on the symptoms of vaginal stenosis.

Up to 5% have synchronous colon primaries.

Location of lesion, size, tethered, circumferential, ulcerated, sphincter tone

Diarrhea requiring parenteral support / severe mucous or blood discharge necessitating sanitary pads / abdominal distention (flat plate radiograph demonstrates distended bowel loops)

Grade 2: Diarrhea requiring parasympatholytic drugs (e.g. Lomotil) / mucous discharge not necessitating sanitary pads / rectal or abdominal pain requiring analgesics