Rectal cancer radiation therapy specification
I. Clinical staging examination before treatment
Necessary examinations.
Blood routine and liver and kidney function.
Frontal and lateral chest radiographs.
CEA.
Barium enema.
Proctoscopy.
Pathological biopsy.
Ultrasound of the abdomen or CT of the abdomen.
CT of the pelvis: liver and abdominal lymph nodes, rectal and pelvic lymph nodes.
Elective examinations.
Endorectal ultrasound.
MRI of abdomen and pelvis.
II. Preoperative radiotherapy
1.Indications for preoperative radiotherapy.
(1) Preoperative clinical stage of T3N0-2M0.
(2) The tumor is ≤6cm from the anus, and the surgeon thinks that the anus cannot be preserved after examination.
2.Treatment methods.
Simultaneous radiotherapy
(1) Radiation therapy.
Whole pelvis irradiation DT45-50Gy, rest 4-6 weeks, then surgery; if surgery is not possible, avoid the small intestine and continue to increase the amount to DT66-70Gy for the remaining tumor.
Irradiation technique: conventional 3-field isocenter irradiation/3D-CRT/IMRT
(2) Simultaneous chemotherapy: conventional treatment of patients with Siroda 1600mg/m2/d in 2 oral doses, from the 1st to the 14th day of radiation therapy, with a 7-day break for one cycle, and 2 cycles during radiation therapy; patients who can be enrolled in the clinical research group will be treated according to each clinical plan.
III. Postoperative radiotherapy
1.Indications for postoperative radiotherapy for T1-2N0M0 tumor localized cut section.
(1) Indications for postoperative radiotherapy after local excision of T1N0 tumor.
Lowly differentiated adenocarcinoma
Non-clear cut edge or near cut edge
with vascular aneurysm tethering
Tumor >4 cm or invasion >1/4 of the intestinal wall
(2) Indications for radiation therapy after local resection of T2N0 tumor.
It is the absolute indication for postoperative radiotherapy
accompanied by the above-mentioned adverse pathological prognostic factors.
2.Indications for radiation therapy after Miles or Dixon radical surgery
Tumor located in the true pelvis
T3-4N0-2
AnyT,N+
3.Treatment method.
Simultaneous radiotherapy
Radiation therapy: total pelvic irradiation DT45-50Gy. irradiation technique: conventional 3 field isocenter irradiation/3D-CRT/IMRT. synchronous chemotherapy: conventional treatment patients with Siroda 1600mg/m2/d in 2 oral doses, from the 1st to the 14th day of radiation therapy, with 7 days rest for one cycle, and 2 cycles during radiation therapy; patients who can be enrolled in clinical research group, according to each Patients who can be enrolled in the clinical research group will be treated according to the clinical plan.
4.Radiation therapy for locally advanced (T4NanyM0) rectal cancer
Indications.
(1) Locally advanced rectal cancer T4N0-2M0.
(2) locally advanced rectal cancer T4N0-2M0, combined with intestinal obstruction, first intestinal obstruction removal surgery.
Treatment method: simultaneous radiotherapy and chemotherapy
Radiotherapy: After irradiating the whole pelvis with DT45-50Gy, if surgery is not possible, the small intestine should be avoided and the residual tumor should be further increased to DT66-70Gy.
Irradiation technique: conventional 3-field isocenter irradiation/3D-CRT/IMRT
Simultaneous chemotherapy: conventional treatment patients with Siroda 1600mg/m2/d in 2 oral doses, from the 1st to the 14th day of radiation therapy, with a 7-day break for one cycle, and 2 cycles during radiation therapy; patients who can be enrolled in the clinical research group will be treated according to each clinical plan.
IV. Radiation therapy techniques
Dose of radiation: The dose of radiation after radical surgery is 50Gy/25 times/5 weeks.
Irradiation method: conventional three-field isocenter irradiation or conformal/intensity-adjusted irradiation
(1) General three-field isocenter irradiation.
Positioning method: inject approximately 20-50 ml of barium through the anus before positioning (Dixon surgery patients) or place a metal marker at the original anus, at the current perineal scar. Prone position, padded with perforated plastic foam board; one posterior and two lateral fields irradiated with a dose ratio of 2:1:1, with a 30-degree wedge-shaped plate in the lateral field.
Scope of irradiation: including the tumor bed, anterior sacral soft tissue, lymphatic drainage area around the internal iliac vessels, and perineal surgical scar. The upper border was the lower edge of the L5 cone, the lower border was the lower edge of the closed foramen (Dixon surgery) or the perineal scar where the metal marker was placed (Mile’s surgery), and the outer true pelvis was placed 1 cm outside. The posterior border of both fields includes the lateral sacral cortex, and the anterior border is 2-3 cm anterior to the anterior rectal wall as shown by contrast (Dixon procedure), or includes the posterior 1/3 of the bladder according to postoperative pelvic CT films (Mile’s procedure).
(2) Conformal/intensity modulated conformal irradiation.
Prep: Oral pantothenic glucosamine 20 ml + 1500~2000 ml of water, 400~600 ml each time. positioning with a perforated foam board pad, prone position, roughly centered on the body surface, scanned at a layer thickness of 0.5 cm, and approximately 50~80 CT images acquired. A CT-enhanced scan is requested, but if the patient is allergic to the contrast agent or is of advanced age or has comorbidities, enhancement may be withheld?
Definition and outlining of the target area.
Clinical target area (CTV): including the tumor bed, anterior sacral soft tissue, external iliac vessels and some common iliac vessels above the upper border of sacral 3, lymphatic drainage area around internal iliac vessels below the upper border of sacral 3, and perineal surgical scars (Mile’s surgery). Specific scope: the upper border is the inferior margin of the L5 conus and the lower border is the inferior margin of the foramen occulta (Dixon’s surgery) or the perineal scar (Mile’s surgery). The lateral border is the inner edge of the true pelvis, the anterior border includes 1/4 to 1/3 of the posterior wall of the filling bladder, and the posterior border includes half of the sacral cortex (above the upper edge of sacral 3) and the posterior edge of the sacral cortex (below the upper edge of sacral 3)
Planned target area (PTV): 1.0 cm expansion on the extent of CTV.
Outlining of normal tissues and organs: including bilateral femoral head, bladder, small intestine within the irradiation range (to be outlined to the upper two uppermost layers of the PTV) and testes.
V. Evaluation of toxic effects
Toxic side effects occurring in simultaneous radiotherapy were evaluated by CTCAEv3.0, mainly in the following areas.
Blood routine.
Gastrointestinal toxic side effects: such as diarrhea, nausea, fecal incontinence, etc.
Others: such as neurotoxic reactions, etc.
VI. Follow up
Physical examination, fecal occult blood, blood routine, blood biochemistry: every 3 months to 2 years, then, every 6 months to 5 years.
CEA: every 6 months to 2 years for patients with positive CEA before treatment, then, every year to 5 years.
Chest radiograph: every 12 months to 5 years; every 6 months to 5 years if liver or abdominal metastases have been resected; every 3 months to 5 years after lung metastases have been resected.
CT of the abdomen: every 6 months to 2 years, then, every year to 5 years.
CT of the chest: every 6 months to 2 years after lung metastasectomy
Colonoscopy: every year to 5 years.