الفهرس 
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Abstract
Colon cancer is considered to be the third most common cancer worldwide and a leading cause of death globally. At diagnosis of colon cancer, 3.7-11% developed bone metastasis. Colon cancer patients after being diagnosed; need surgical removal of the tumor with adjuvant chemotherapy. There is an obvious need for alternative approaches that would reduce the cost and serious side effects of chemotherapy. Diet based strategies are important for prevention of colon cancer. B17, commonly known as Laetrile or Amygdalin, is considered to be a potential natural chemo-preventive found in the seeds of common fruits such as apricots, peaches, plums, and apples. The main objective in our work was to study the role of vitamin B17 in a DMH model of colon cancer.
Material & Methods
Eighty young adult male albino rats were used in this study and were divided into the following groups:
group I (Control group): consisted of ten rats; they were equally subdivided into subgroup Ia (kept without any treatment until the end of the study) & Ib (received 1mM EDTA intra-peritoneal once weekly until the end of the study).
group II (Vitamin B17 group): consisted of ten animals; they received the calculated dose of vitamin B17 orally daily for five weeks
group III (Colon cancer induced group): consisted of twenty animals, received DMH I.P in a dose of 20 mg/kg body weight once weekly for five weeks.
group IV (Protected group): consisted of twenty animals; each animal received first the calculated dose of vitamin B17 orally daily for five weeks, then stopped and colon cancer was induced by a 20 mg/kg body weight I.P dose of DMH for the following five weeks.
group V (Treated group): consisted of twenty animals; colon cancer was induced first with DMH I.P injection in a dose of 20 mg/kg body weight for five weeks, and then received the calculated dose of vitamin B17 for five consecutive weeks.
The animals were weighed at the beginning of the experiment then; regular observation for their physical activity and food intake was performed. At the end of the study (ten weeks) and before scarification, the final body weight was recorded and blood samples were taken from the retro-orbital plexus for estimation of liver enzymes (AST & ALT) and CEA levels.
The distal colon and the lumbar vertebrae were excised, washed and fixed for further histological studies:
• For light microscopic examination: Paraffin blocks were prepared & 3-5 μm colon sections were cut and subjected to H&E for routine histological examination, special stains (Masson trichome stain for detection of collagen fiber deposition & Toluidine blue for detecting bone mineralization) and immuno-histochemical stains (Ki-67, Ck20, VEGF-A & CDx2).
• For Scanning Electron Microscopic examination: The specimens were mounted on aluminum slabs using silver conductive paint and gold palladium sputter coating and were examined under Scanning Electron Microscope.
Morphometric studies were done using image analyzer software for Goblet cells
number & Mitotic index (H&E stained colon sections), number of bone resorption pits (H&E stained bone sections), Masson trichome stain: percentage of positively stained surface area, Toluidine blue stain: color intensity & immune-stains: percentage of ki-67 immuno-positive nuclei, percentage of Ck20 immuno-positive nuclei, area percentage of VEGF & percentage of surface area of CDX2 positive immune-staining in all groups.
Results:
General & biochemical results:
Both Control and Vitamin B17 groups showed normal physical activity, normal food intake, and significant weight gaining all over the study, normal AST, ALT & CEA levels. Colon cancer induced group showed marked decrease in physical activity, lethargy, marked decrease in food intake, a highly significant decrease in their final body weight and highly significant elevation in AST, ALT & CEA levels when compared to the control group. Recorded death rate was 20%. The protected group showed nearly normal physical activity, average food intake, a non-significant difference between their final body weight and their initial one and a non-significant elevation in AST, ALT & CEA levels when compared to the control group. No deaths occurred among this group. The treated group showed decreases in their physical activity, decreased food intake and a highly significant decrease in their final body weight. Recorded death rate was 30%.
Histological results:
In comparison with the control group, both colon cancer induced & treated groups showed invasion of the colonic tissue by pleomorphic branching colonic glands of variable shapes and sizes lined with dysplastic elongated hyperchromatic nuclei with frequent mitotic figures or stratified multilayered crowded nuclei with an extremely significant (p˂0.0001) reduction of goblet cell number when compared to the control group. Major pathological bone osteolytic changes and invasion of bone marrow spaces by malignant cell nests were observed in colon cancer induced & the treated groups. While the protected group showed impressive improvement of all previously mentioned parameters.