Colorectal Cancer: Risk Factors, Pathogenesis, and Spread
Colorectal cancer, the second most common malignancy globally, affects millions annually. Risk factors include diet, obesity, and smoking, with most cases in elderly individuals. The pathogenesis involves a stepwise progression from precursor lesions, leading to increasing dysplasia. The tumor can originate from adenoma or papilloma, with pathological histology ranging from well-differentiated to highly undifferentiated adenocarcinoma. Local spread occurs circumferentially over time. Anterior penetration can affect surrounding structures.
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Presentation Transcript
MALIGNANCY OF THE RECTUM COLORECTAL CANCER IS THE SECOND MOST COMMON MALIGNANCY, AFFECTING MORE THAN 1 MILLION PEOPLE EVERY YEAR IT IS THE SECOND MOST COMMON CANCER IN WOMEN AND THE THIRD MOST COMMON CANCER IN MEN, BEING THE FOURTH MOST COMMON CAUSE OF CANCER DEATH AFTER LUNG, STOMACH, AND LIVER CANCER.
RISK FACTORS INCLUDE DIET, OBESITY, SMOKING AND LACK OF PHYSICAL EXERCISE. MOST COLORECTAL CANCERS ARE DUE TO OLD AGE. WITH AROUND 60% OF CASES AFFECTING PATIENTS 70 YEARS OR OLDER
PATHOGENESIS COLORECTAL CANCER ORIGINATES FROM PREMALIGNANT PRECURSOR LESIONS IN THE EPITHELIAL LINING OF THE COLON OR RECTUM IN A STEPWISE PROGRESSION THAT RESULTS IN INCREASING DYSPLASIA DUE TO AN ACCUMULATION OF GENETIC ABNORMALITIES THIS IS REFERRED TO AS THE ADENOMA CARCINOMA SEQUENCE
ORIGIN OF THE TUMOR : ADENOMA OR PAPILLOMA OF THE RECTUM IS PRECANCEROUS CONDITION . THERE IS SOME TIMES ONE OR MORE SYNCHRONOUS TUMOR WITH RECTAL CARCINOMA. GENETIC CHANGES TO ADENOMA TO SEVERE DYSPLASIA TO CARCINOMA .( ADENOMA CARCINOMA SEQUENCE)
PATHOLOGICAL HISTOLOGY : WELL DIFFERTIATEDADENOCARCINOMA. AVERAGELY DIFFERTIATEDADENOCARCINOMA. ANAPLASTIC ,HIGHLY UNDIFFERENTIATED ADENOCARCINOMA
PAPILLOFEROUS STENOTIC OR INFILTRATIVE ULCERATIVE
TYPE OF SPREAD LOCAL SPREAD : CIRCUMFERENTIALLY RATHER IN A LONGITUDINAL DIRECTION PERIOD OF 6 MONTHS INVOLVE QUARTER OF THE CIRCUMFERENCE .AND 18 MONTHS UP TO 18 MONTH ..COMPLETE CIRCUMFERENCE
IF THE PENETRATION OCCUR ANTERIORLY THE PROSTATE ,SEMINAL VESICLE ,BLADDER IN MALE . IN FEMALE THE VAGINA ,UTERUS INVADED . IN BOTH SEX LATERALLY TO THE URETER. POSTERIORLY TO THE SACRUM AND SACRAL PLEXUS . DOWNWARD RARE EXCEPT FOR ANAPLASTIC TUMOR.
LYMPHATIC SPREAD MOST OF THE LYMPHATIC FOLLOW THE BLOOD SUPPLY . IN THE UPPER HALF ABOVE THE PERITONEAL REFLECTION ,UP TO THE PARA AORTIC .. THE LOWER HALF UP TO 1-2 CM FROM THE ANUS STILL DRAINING UP WARD BUT FIRST IN THE PARA RECTAL LN. MIDDLE RECTAL ARTERY, PRIMARY LATERAL SPREAD TO THE PELVIC WALL LYMPHATICS OCCURS IN AROUND 20% OF CASES.
VENOUS SPREAD THE BLOOD BORN METASTASIS: LIVER 34% LUNG 22% ADRENAL 11% 33% REMAINING INCLUDE DIFFERENT SITE INCLUDING THE BRAIN.
PERITONEAL DISSEMINATION MAY FOLLOW THE PERITONEAL COAT BY HIGH LAYING RECTAL CARCINOMA.
STAGING OF RECTAL CANCER DUKES STAGING : A-THE GROWTH IS EXTENDED TO THE RECTAL WALL. B- THE GROWTH IS EXTENDED TO EXTRA RECTAL TISSUES ,BUT NO METASTASIS TO REGIONAL LYMPH NODES. C TO THE REGIONAL LYMPH NODE : C1,C2. IN WHICH THE NODES ACCOMPANYING THE SUPPLYING BLOOD VESSELS TO THEIR ORIGIN FROM THE AORTA ARE INVOLVED D ADDED TO DUKES INCLUDE THE DISTANT METASTASIS .
CLINICAL FEATURES OF RECTAL CANCER THE AGE OF PRESENTATION IS USUALLY ABOVE 55 YEARS EARLY SYMPTOMS OF RECTAL CANCER: BLEEDING PER RECTUM TENESMUS EARLY MORNING BLOODY DIARRHEA LATE SYMPTOM : 1-PAIN IS DUE TO SOME DEGREE OF INTESTINAL OBSTRUCTION DUE TO TUMOR IN THE RECTO SIGMOID REGION .ALSO THE PAIN DUE TO INVASION THE PROSTATE ,URINARY BLADDER .THE BACK OR SCIATICA WHEN INVADE THE SACRAL PLEXUS . 2-WIGHT LOSS DUE TO HEPATIC METASTASIS.
INVESTIGATIONS DIAGNOSIS AND ASSESSMENT OF RECTAL CANCER: DIGITAL RECTAL EXAMINATION SIGMOIDOSCOPY AND BIOPSY COLONOSCOPY IF POSSIBLE (OR CT COLONOGRAPHY OR BARIUM ENEMA). ALL PATIENTS WITH PROVEN RECTAL CANCER REQUIRE STAGING BY: IMAGING OF THE LIVER AND CHEST, PREFERABLY BY CT LOCAL PELVIC IMAGING BY MAGNETIC RESONANCE IMAGING AND/OR ENDOLUMINAL ULTRASOUND.
INVESTIGATION RECTAL EXAMINATION IN MANY CASES WHERE THE NEOPLASM IS SITUATED WITHIN 7 8 CM OF THE ANAL VERGE IT CAN BE FELT ON DIGITAL RECTAL EXAMINATION AS AN ELEVATED, IRREGULAR AND HARD END LUMINAL MASS WHEN THE CENTER ULCERATES, A SHALLOW DEPRESSION WILL BE FELT WITH RAISED AND EVERTED EDGES. RIGID SIGMOIDOSCOPY COLONOSCOPY (TO EXCLUDE A SYNCHRONOUS TUMOUR) IMAGING OF THE CHEST, ABDOMEN AND PELVIS, PREFERABLY BY CT LOCAL PELVIC IMAGING BY MAGNETIC RESONANCE IMAGING AND/OR END LUMINAL ULTRASOUND
TREATMENT SURGICAL EXCISION OF THE TUMOUR IS THE CONVENTIONAL MANAGEMENT OPTION, PROVIDED THIS CAN BE ACHIEVED WITH CLEAR ONCOLOGICAL MARGINS AND ACCEPTABLE RISK OF MORBIDITY AND MORTALITY. BEFORE TREATMENT CAN BE PLANNED, IT IS NECESSARY TO ASSESS: THE FITNESS OF THE PATIENT; THE EXTENT OF SPREAD OF THE TUMOUR. RADICAL EXCISION OF THE RECTUM, TOGETHER WITH THE MESORECTUM AND ASSOCIATED LYMPH NODES, SHOULD BE THE AIM IN MOST CASES.
SURGERY FOR RECTAL CANCER SURGERY IS THE MAINSTAY OF CURATIVE THERAPY THE PRIMARY RESECTION CONSISTS OF RECTAL RESECTION PERFORMED BY TOTAL MESORECTAL EXCISION MOST CASES CAN BE TREATED BY ANTERIOR RESECTION, WITH THE COLORECTAL ANASTOMOSIS BEING ACHIEVED WITH A CIRCULAR STAPLING GUN A SMALLER GROUP OF LOW, EXTENSIVE TUMOURS REQUIRE AN ABDOMINOPERINEAL EXCISION WITH A PERMANENT COLOSTOMY PREOPERATIVE RADIOTHERAPY WITH OR WITHOUT CHEMOTHERAPY CAN BE USED TO DOWN-STAGE THE CANCER AND REDUCE LOCAL RECURRENCE
ADJUVANT CHEMOTHERAPY CAN IMPROVE SURVIVAL IN NODE- POSITIVE DISEASE LIVER RESECTION IN CAREFULLY SELECTED PATIENTS OFFERS THE BEST CHANCE OF CURE FOR SINGLE OR WELL-LOCALISED LIVER METASTASES
PREOPERATIVE PREPARATION MECHANICAL BOWEL PREPARATION COUNSELING AND SITTING OF STOMAS CORRECTION OF ANEMIA AND ELECTROLYTE DISTURBANCE CROSS- MATCHING OF BLOOD PROPHYLACTIC ANTIBIOTIC DEEP VEIN THROMBOSIS PROPHYLAXIS INSERTION OF URETHRAL CATHETER
CARCINOID TUMOR THE LESION IS SUB MUCOUS LIKE LYMPHOMA .. LESS COMMON THAN THE CARCINOID OF SMALL INTESTINE. THE INCIDENCE OF MALIGNANCY AND DISTANT METASTASIS LESS 10% SLOWLY GROWING TUMOR ,METASTASIS IS LATE THE SIZE OF >2 CM IS MALIGNANT
