Radiation Oncology In-service Exam Review: GI Cancers

The treatment of choice for gastric MALT is antibiotics directed at H. pylori. This is because gastric MALT lymphoma is often associated with H. pylori infection, and eradicating the infection with antibiotics has been shown to lead to remission in many cases. Low dose RT alone, chemotherapy alone, and surgical resection followed by chemoradiation may be considered in certain cases, but antibiotics directed at H. pylori is the preferred initial treatment option.

Trousseau's sign is migratory thrombophlebitis, sister maty joseph nodule is umbilicus nodule, Irish's node is axillary adenopathy

PA field: superior: L5/S1; Inferior inferior obturator foramen or 3 cm below tumor; Lateral: 1.5 cm outside pelvic inlet
Lateral fields: posterior: behind bony sacrum; anterior: posterior pubic symphasis if T3, anterior pubic symphasis if T4

Rectal cancer metastases can reach the liver through the superior rectal vein. The superior rectal vein drains blood from the rectum and it ultimately joins the portal vein system, which carries blood to the liver. This allows cancer cells from the rectum to travel through the bloodstream and establish metastases in the liver. The other options, such as the inferior rectal vein, middle rectal vein, and inferior mesenteric vein, are not the primary routes for liver metastases in rectal cancer.

The major finding of the GITSG 91-73 trial for pancreatic cancer was that the addition of adjuvant CRT (chemoradiotherapy) with 5-FU (fluorouracil) and a 40 Gy split course to surgery improved the 5-year overall survival (OS) rate from 5% to 14% in resectable pancreatic cancer. This means that patients who received this treatment had a higher chance of surviving for 5 years compared to those who did not receive the adjuvant CRT.

Both the German and Dutch trials showed LRR improvements but no OS benefit to pre-op RT. Swedish trial showed OS improvement of 48% vs 58% at 5 years. GITSG evaluated post-op RT vs post-op CRT, which improved OS.

The appropriate dosing of concurrent 5-FU when given with RT for rectal cancer is 225 mg/m2 over 24 hours, 7 days per week during RT.

25/5 was used as pre-op treatment in the Duth and Swedish rectal cancer studies; the post-op arm of the German trial included at 5.4 Gy boost.

The randomization of the GITSG 91-73 trial for pancreatic cancer was comparing surgery alone to surgery followed by chemoradiation with a 40 Gy split course and concurrent 5-FU. This means that patients were randomly assigned to either undergo surgery alone or undergo surgery followed by a combination of radiation therapy with a split course of 40 Gy and concurrent administration of 5-FU chemotherapy. The purpose of this trial was to determine the effectiveness of adding chemoradiation to surgery in the treatment of pancreatic cancer.

The correct answer is that chemoradiation with 5-FU and mitomycin improved 3 year LC (local control) from 36% to 59% as compared to radiation therapy alone. This means that the addition of chemotherapy with 5-FU and mitomycin to radiation therapy resulted in a significant improvement in the control of the tumor at the local site. The study found that this combination treatment was more effective in preventing the recurrence or progression of anal cancer compared to radiation therapy alone.