Rectum Lecture 3 Malignancy of the rectum - PowerPoint Presentation

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Rectum

Lecture 3

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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.

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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

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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

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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

)

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Pathological histology :

Well

differtiated

adenocarcinoma.

Averagely

differtiated

adenocarcinoma.

Anaplastic ,highly undifferentiated adenocarcinoma

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Papilloferous

Stenotic or infiltrative

Ulcerative

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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

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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.

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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.

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Venous spread

The blood born metastasis:

Liver 34%

Lung 22%

Adrenal 11%

33% remaining include different site including the brain.

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Peritoneal dissemination

May follow the peritoneal coat by high laying rectal carcinoma.

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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 .

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Tnm

staging

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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.

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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.

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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

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CT scan of the pelvis

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EUS MRI

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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.

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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

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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

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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

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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