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44 Cards in this Set

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Describe the fields for an anal ca.
Example of radiation fields used to cover pelvic nodes and primary cancer. Upper border generally lowered from lumbosacral junction to lower border of sacroiliac joints part way through course. Fields are later reduced further to give higher dose to primary tumor. Separate anterior fields are applied to cover lateral inguinal nodes.




Fields as per RTOG 9811
Initial pelvic field (treat to 30.6 Gy)
Superior L5/S1
Inferior Include the anus with a minimum margin of 2.5 cm around the anus and tumor.
Lateral (AP field) include the lateral inguinal nodes
Lateral (PA field) 2 cm lateral to greater sciatic notch (will not include the lateral inguinal region but spares femoral heads)
Notes If patient is N0 then can come off of the inguinals at 36 Gy

Reduced Pelvic Field #1 (treat to 45 Gy)
The superior border shall be dropped to the upper level of the greater sciatic notch (inferior border of SI joints)
Reduced Pelvic Field #2 (For all T3,T4, and N+ patients or T2 patients with residual disease after 45 Gy) (treat to 55-59 Gy)
boost fields shall be utiized to encompass the original primary tumor volume plus a 2.0 to 2.5 cm margin. If inguinal/pelvic nodes are grossly involved they should be included in the final boost field if small bowel can be avoided.
What is the significance of the dentate line in terms of lymph node drainage?
Mucosa above dentate drains to perirectal/internal iliac nodes; below dentate line to inguinal nodes
What % of anal cancer patient present with positive lymph nodes?
25-35 %
What is the occult positivity rate for inguinal nodes (i.e. if clinically negative) in anal cancer?
10-15%
What is the rate of extrapelvic visceral mets at presentation for anal cancer?
5-10%
What does the work-up for anal cancer patients include?
H&P (including gyn exam for women including cervical ca screening), Labs (HIV if risk factors), imaging, biopsy of lesion
What imaging studies are typically done for anal cancer patients?
Trans-anal US (to assess for perirectal nodes), CXR or CT of chest, PET/CT or CT of abdomen and pelvis
What features of anal lesions needs to be appreciated on physical exam? Why?
Degree of circumferential involvement and anal sphincter tone; may dictate treatment
What is the T-staging for anal cancer based on? Define T1-4.
Size of lesion; T1 <2 cm, T2 2-5 cm, T3 > 5 cm, T4 invasion of adjacent organs
Most patients with anal cancer present with what T stage?
T2 or T3
What N stage is an anal cancer patient with perirectal and inguinal LA?
N3
What N stage is an anal cancer patient with bilateral inguinal or internal iliac LA?
N3-mets in perirectal and inguinal LN and or bilateral int iliac +/- inguinal LN
What anal cancer patients have AJCC stage III disease?
N+ or T4 patients
What are the OS and sphincter preservation rates for all-comers with anal cancer at 5 yrs?
70%, 70%
What are the criteria for local excision alone in anal cancer? What are the LC rates in such carefully selected pts?
Small T1 lesion (<2cm), well-differentiated, - margins, <40% circumferential involvement, compliant patients; LC >90% in selected patients (per Boman et al, Cancer 1984 and Greenall, Br J Surg 1985)
What was the standard surgical procedure for anal cancer before the advent of CRT? What was the disadvantage of this approach?
APR; required colostomy (i.e. loss of sphincter function)
What chemo doses are used in anal cancer and what is the scheduling?
5-FU 1000 mg/m²/d IV on days 1-4 and 29-32; Mitomycin 10 mg/m² IV bolus on days 1 and 29
Chemo is given concurrent with RT.
For which anal cancer patients is APR currently used?
As salvage for patients who fail chemo/radiation, or who had prior pelvic RT
What anal cancer study randomized to CRT with 5-FU/Mitomycin vs. 5-FU alone? What did it find?
RTOG 87-04 (Flam M et al, JCO 1996); found no difference in OS, but Mitomycin improved CR rate (92% vs. 85%) and colostomy rate (9% vs. 22%) at 4 yrs
What are the recurrence rates after definitive CRT for anal cancer and what are the salvage rates at 5-yrs?
30%; 40-60%
How is the anal cancer patient simulated for the AP/PA RTOG technique?
Supine, frog legged, hips immobilized, full bladder, legs apart with rectal tube and anal BB, bolus over inguinal nodes, po contrast 90 minutes earlier to visualize small bowel
How is the AP field different from the PA field for the AP/PA RTOG technique in anal cancer?
AP is wider (to edge of greater trocheanter) than PA field (spares femoral heads); AP field is typically of greater energy (18 MV) than PA field (6 MV)
Per 98-11, which anal cancer patients need to receive a boost beyond 45 Gy?
Patients with T3, T4, or N+ lesions or T2 lesions with residual disease after 45 Gy
What is the dose per fx for anal cancer per RTOG 98-11?
1.8 Gy/fx to 45 Gy for initial, 2 Gy/fx to 55-59 Gy total for CD portion
What is the minimum prescription depth for adequate inguinal node coverage in anal cancer?
3 cm--this means at least 12 MeV would be needed to get the 90 % IDL to 12/4=3
How far caudally should inguinal nodes be covered in anal cancer?
To lesser trochanter
What is the mean time to tumor regression after CRT for anal cancer?
3 mos (but can be up to 12 mos), therefore, no benefit to routine post-Tx biopsy (Cummings BJ et al, IJROBP 1991)
How long after CRT, should an anal cancer patient undergo a biopsy?
If mass increases in size or new symptoms (pain, bleeding, ect.). The mean time to tumor regression is 3 months although it can take up to 12 months so I don't recommend "routine" biopsy.
What radiation dose should bowel be kept under in anal cancer patients?
45-50.4 Gy
What is the main toxicity of Mitomycin?
Hematological
Most anal cancer recurrences occur within what time-frame?
2 yrs
Why is the lateral border of the PA field narrower than the AP in treating anal and vulvar cancer?
The lateral inguinal nodes are not routinely treated in the PA field to allow adequate sparing of the femoral heads.
Describe the change in the field for anal cancer after the initial 30.6 Gy is delivered.
After 30.6 Gy, the superior field extent is reduced to the bottowm of the SI joints for the last 14.4 Gy (eight fractions) to 45 Gy. There is also another field reduction at 36 Gy off node negative inguinals.
For patients treated with an AP-PA technique rather than 4-field for anal cancer, how is the lateral inguinal region brought to the minimum dose of 36 Gy?
Use an anterior electron boost, matched to the PA exit field to bring the lateral inguinal region to the minimum dose of 36 Gy.
Which patients with anal cancer get a boost beyond 45 Gy? Describe the boost.
All pts with T3-T4, N+ or patients with T2 residual disease after 45 Gy, the intent is to deliver an additional boost of 10-14 Gy to a total dose of 55-59 Gy (boost dose goes to 2 Gy/d vs 1.8 Gy/day for initial 45 Gy). The target volume for the second boost field (boost beyond 45Gy) is GTVprimary and nodes pluse 2-2.5 cm margin. The field options include 4 field vs PA/lats vs direct perineal boost with electrons with pt in lithotomy position.
What if you have a residual anal mass at the end of treatment?
Per RTOG 98-11, you can boost to 59.4
Pt has recurrent anal cancer (has already received full-dose CTX-RT).
What do you recommend?
APR is standard. Other options include implant or excision.
How do you manage acute SE from RT for anal cancer?
Proctofoam, cortisone, silvadine, Sitz baths, Domboro soaks.
Describe the LN drainage for anal cancer.
LN drainage – depends on location
Above dentate line: drain to the perirectal and paravertebral LN
Below dentate line: drain to the inguinal and femoral LN
How should anal adenocarcinoma be approached?
Behaves worse than anal scc. Should treat like rectal with pre-op chemo-rt followed by APR.
Stage and group for a squamous cell anal tumor with size 6 cm and a met in perirectal lymph nodes.
T3 is greater than 5 cm
N1 is perirectal LN
T3N1=IIIA
Staging and group for anal tumor that invades vagina or urethra and has positive inguinal and perirectal nodes.
T4 invades adjacent structure such as bladder, vagina, urethra
N3 is bilateral inguinals or inguinal plus perirectal or bilateral int iliac
T4N3 is IIIB
If an HIV+ patient with anal cancer has CD-4 count less than 200, what adjustments are made in treatment?
1) SMALLER FIELD: start with top border at bottom of SI joints,
2) REDUCE CHEMO DOSES: Second dose of MMC may be held and the 5_FU may be dose-reduced
3) XRT Dose may be decreased: final dose may be 50 GY instead of 55-59
What is the anal verge?
The anal verge is the distal end of the anal canal, forming a transitional zone between the skin of the anal canal and the perianal skin.