Surgery SC013: Surgery May Cure Your Cancer: Surgical Oncology Flashcards
Cancer
- Aberration of cell growth
- Cell survive and multiply indefinitely
- Growth without the orderly histology of primary organ
- Non-functional
- Spread, invade, destroy tissue locally
- Spread to distant organs via blood stream, lymphatics, nerve fibres, peritoneum
- Replace and destroy distant organs
6 mutations converting normal cell into cancer cell:
- Self-sufficiency in growth signals
- Insensitivity to anti-growth signals
- Evading apoptosis
- Limitless replicative potential
- Sustained angiogenesis
- Tissue invasion and metastasis (pathogenesis: Primary malignant neoplasm —> vascularisation —> tumour growth —> invasion —> transport —> metastasis)
Spread of cancer:
- Local
- Primary site, adjacent tissues / organ (e.g. diaphragm, colon (if HCC segment 5), stomach (if HCC segment 2/3)) - Regional
- LN
- Perineural - Distant
- Lung
- Bone
- Transperitoneal
***Causes of mortality related to cancer
- Cancer invasion of organ of origin, adjacent organs / distant sites —> Loss of organ function (e.g. Liver failure, Intestinal obstruction)
- Cancer cachexia
- Esophageal cancer
- Pancreatic cancer
- Liver cancer
Cancer cachexia
- Anorexia
- Progressive, involuntary weight loss
- Muscle wasting, lethargy, malnutrition
- Anergy
- Infection (e.g. chest infection)
- Terminal event
***Why is surgery able to cure cancer?
Surgery not only remove cancer —> also adjourning tissues / organs + regional lymphatic that are sites of spread of most cancers
Scope of cancer surgery:
- Cancer itself
- A rim of tissues containing no gross tumour (aka Tumour-free resection margin)
—> In order to remove ***microscopic spread + regional LN
***Deficiencies of surgery in treating cancer
Why surgery cannot produce 100% survival rate?
- Morbidity + Mortality related to operation could be significant
- ***Microscopic spread via blood stream / lymphatic is already present at time of surgery —> Radical surgery can eradicate lymphatic spread but not haematogenous spread to distant organ
- New growth / Recurrence from occult foci is still possible even after curative operation
- Resection tumour-free margin is not always attainable because cancer is close to ***indispensable viscera / blood vessels
- Mobilisation of cancer / organ bearing the cancer may lead to dissemination of cancer cells
- Loss of organ / limb / tissue function may affect QoL / lead to early demise
Other deficiencies:
- Disfigurement may induce psychological disturbance
- Not all cancer can be treated by surgery when discovered
***Principles of operation for cancer
- Complete extirpation of tumour with a rim of tumour-free tissues (aka good ***tumour-free resection margin) (margin >1cm)
- Clearance of lymphatic drainage (e.g. regional LN, sentinel LN) which may harbour microscopic / macroscopic spread
- En-bloc resection of primary tumour with adjacent resectable organ / tissue
- Minimum manipulation of tumour and tumour bearing organ
- Preservation of organ function
- Minimum blood loss + Avoid blood transfusion
- blood transfusion can compromise immunological functions —> avoid whenever possible
Anterior vs Conventional approach in Surgery for HCC
Anterior approach:
- Separate tumour lobe from other lobes from the front first
Convention approach:
- Ligate vessels behind the liver first by lifting right lobe up
Risk of conventional approach for right hepatectomy:
- Tearing of right hepatic vein
- Twisting of inflow and outflow pedicles
- Dissemination of cancer cells into systemic circulation
- Iatrogenic rupture of soft tumour e.g. HCC
***Local ablative therapy for cancer
- Absolute alcohol injection
- Radiofrequency ablation
- Microwave ablation
- High intensity focused ultrasound (HIFU)
Organ function loss after surgery
Reasons:
- Part of organ bearing the tumour has been removed
- Physiological disturbance induced by massive bleeding
Effect:
- Poor QoL
- Need for medication
- ↑ Hospital cost
- ↑ Mortality
***Effects of major bleeding
Hypotension —> Hypoperfusion of major organs —> Post-operative organ failure —> Need for massive blood transfusion —> Chance of recurrence
***Blood transfusion and Cancer recurrence
Blood transfusion
—> Immunosuppression
—> Loss of immune control of cancer cell growth induced by blood transfusion (∵ Transfused histocompatibility antigen induces specific immunologic non-reactivity)
—> Rapid growth of microscopic spread / foci of cancer after surgery
***Measurement of outcome of surgery
- Hospital mortality rate (death within the same hospital admission for surgery, irrespective of cause of death / duration of hospital stay)
—> more accurate than 30-day operative mortality rate because many patients can survive >30 days in ICU until complications that eventually die - 30-day operative mortality rate
- 5-year disease-free survival rate (i.e. surviving without recurrence of cancer)
- 5-year overall survival rate (i.e. surviving after the operation irrespective of the cause e.g. having recurrence will still be counted as survivor)
- QoL
Current survival statistics of cancer treatment
Hospital mortality rate: 1-5%
5-year survival rate:
- Breast cancer: 85%
- Colon cancer: 50%
- Lung cancer: 45%
- Liver cancer: 60%
- Pancreatic cancer: 20% (∵ tendency to spread via lymphatics + nerve)
Liver cancer: When is cancer considered cured?
Recurrence usually occur within first 5 years —> If no extrahepatic recurrence beyond 5 years —> considered cured
***Determinants of patient survival / Factors contributing to success / failure of surgical treatment for cancer
- TNM stage of tumour at time of surgery
- Surgical technique, Blood loss volume, Requirement of blood transfusion (dependent on experience + technique of surgeon + difficulty of operation)
- Completeness of tumour clearance
- Function of organ remnant
- Close surveillance after surgery (e.g. look for second primary)
- Prompt treatment of recurrence
- Compliance of patient to treatment + follow-up
