GC202 Surgery May Cure Your Cancer Surgical Oncology - Notes
Surgical oncology is the branch of surgery dedicated to the diagnosis, staging, and curative or palliative resection of solid tumors, often integrated with multimodal cancer therapies.
Surgical Oncology: Surgery May Cure Your Cancer
The Big Idea: Surgery is the most effective method of cancer therapy currently available. [1] This lecture, delivered by Professor SC Chan for the Senior Clerkship (WCS No. 13), lays out the fundamental principles of why and how surgery cures cancer—and why it sometimes fails. It is a conceptual, principles-based lecture rather than a site-specific surgical techniques lecture. The examiners love testing the "why" behind surgical oncology principles because these concepts cut across every cancer surgery question in MCQs, SAQs, and minicases.
Learning Objectives (derived from lecture structure):
- Understand why surgery can cure cancer and what limits its success
- Define and differentiate outcome measures in cancer surgery
- Know 5-year survival rates for major cancers treated by surgery
- Articulate the basic principles of cancer surgery
- Understand determinants of survival after cancer surgery (TNM, blood loss, organ function)
- Appreciate the role of surveillance and adjuvant therapy in preventing/treating recurrence
How it fits in: This lecture is the "umbrella" under which all site-specific cancer surgery lectures sit. When you encounter questions about colorectal, breast, gastric, liver, head & neck, or lung cancer surgery, the principles taught here are being tested. The lecture connects directly to GC 194 (colorectal cancer), GC 181 (breast cancer), GC 212 (gastric cancer), GC 077 (lung cancer), and the advanced liver surgery lecture.
Core Concepts and Mechanisms
"Surgery not only can remove the cancer itself but also the adjoining tissues/organs and the regional lymphatic that are sites of the spread of most cancers." [1]
First-Principles Understanding
Cancer spreads in two main ways: (1) local/lymphatic spread — cancer cells invade surrounding tissue and track along lymphatic channels to regional lymph nodes; (2) hematogenous spread — cancer cells enter blood vessels and seed distant organs. Surgery can physically excise the primary tumour, the surrounding tissue (to clear microscopic local invasion), and the regional lymph nodes (to clear lymphatic spread). However, surgery CANNOT chase cancer cells that have already entered the bloodstream and seeded distant organs — that is where systemic therapy comes in.
The scope of cancer surgery therefore includes three components:
| Component | Purpose | Why It Matters |
|---|---|---|
| The cancer itself | Remove the gross tumour | Obvious — you must remove the visible disease |
| A rim of tumour-free resection margin | Remove microscopic invasion beyond the visible tumour | Cancer cells extend beyond what the eye can see; a clear margin means no cancer at the cut edge |
| Regional lymph nodes | Clear lymphatic drainage | Lymph nodes are the first relay stations for cancer spread; removing them removes potential metastatic deposits |
The outcome of surgery for cancer can be measured by five metrics. [1]
| Metric | Definition | Key Points |
|---|---|---|
| Hospital mortality rate | Number of patients who die during the same hospital admission for surgery, irrespective of cause of death or duration of stay | More accurate reflection than 30-day mortality because many patients survive > 30 days in ICU but die of complications that will eventually kill them [1] |
| 30-day operative mortality rate | Number of patients who die within 30 days of surgery | Standard benchmark but can underestimate true operative mortality for complex cases |
| Disease-free survival (DFS) | Proportion of patients surviving without recurrence of cancer | The purest measure of whether surgery "cured" the cancer |
| Overall survival (OS) | Proportion of patients surviving after surgery irrespective of cause; patients surviving with recurrence are still counted as survivors | Can overestimate surgical success because patients may be alive but with active cancer |
| Quality of life (QoL) | How the patient's life is affected by the operation | Increasingly important — a patient alive but with devastating functional loss may not consider themselves "cured" |
Exam Trap
Students frequently confuse disease-free survival with overall survival. Remember: DFS excludes patients with recurrence; OS includes everyone alive regardless of cancer status. A patient with liver metastases who is alive at 5 years counts toward OS but NOT toward DFS.
"The 5-year survival rate varies with the type and stage of the cancer. It tends to be better for early-stage cancer." [1]
| Cancer Type | Approximate 5-Year OS After Surgery |
|---|---|
| Breast | ~85% |
| Liver | ~60% |
| Colon | ~50% |
| Lung | ~45% |
High Yield
These numbers are from the lecture and are the ones the examiners expect. They are approximate and apply to surgically treated patients across all stages. Real-world stage-specific survival varies widely (e.g., Stage I colon cancer may have > 90% 5-year OS, while Stage IV has < 10%).
Six reasons are given why surgery is not 100% curative. [1]
| # | Reason | Explanation from First Principles |
|---|---|---|
| i | Operative mortality | Every major operation carries a risk of death from anaesthesia, hemorrhage, or organ failure. More complex operations (e.g., Whipple, major hepatectomy) carry higher mortality. |
| ii | Microscopic hematogenous/lymphatic spread already present at time of surgery | By the time the cancer is detected and surgery performed, cancer cells may already be circulating in the blood. Surgery can eradicate lymphatic spread (via lymph node dissection) but cannot eradicate hematogenous spread to distant organs — this is the fundamental limitation. |
| iii | New growth or recurrence from occult foci | Even after "curative" resection, tiny nests of cancer cells invisible to the naked eye and imaging may persist and grow into clinical recurrence. |
| iv | Tumour-free resection margin not always attainable | When the cancer abuts indispensable viscera or blood vessels (e.g., portal vein, IVC, aorta), the surgeon cannot cut through these structures, so the margin may be positive. |
| v | Mobilization of cancer may disseminate cancer cells | Surgical handling, manipulation, and mobilization of the tumour-bearing organ can squeeze cancer cells into lymphatics or blood vessels — iatrogenic dissemination. This is why "minimum manipulation" is a surgical principle. |
| vi | Loss of organ/tissue function | Removing a large portion of an organ (e.g., 80% hepatectomy) may cause organ failure (liver failure) that contributes to early death even if the cancer is technically "removed." |
Five principles to improve patient survival rate. [1]
| Principle | Why It Matters |
|---|---|
| i. Complete extirpation of tumour with a good tumour-free resection margin | Positive margins → local recurrence → death. The margin must be adequate (varies by site: e.g., 5 cm for colon, 2 cm distal for rectal, 1 cm for breast lumpectomy, 1 mm CRM for rectal) [2][3] |
| ii. Minimum manipulation of tumour and tumour-bearing organ | Every touch, squeeze, or pull on the tumour can dislodge cancer cells into the circulation. The "no-touch isolation technique" was pioneered for this reason — ligate blood vessels and lymphatics BEFORE mobilizing the tumour. |
| iii. Clearance of lymphatic drainage (may harbour microscopic or macroscopic spread) | Lymph nodes are the first "filter" for cancer cells. Removing them provides staging information (N stage) and therapeutic benefit if they contain tumour. Minimum 12 nodes for colon cancer adequate staging [2]. |
| iv. Minimum disruption of organ function | The goal is to remove the cancer while preserving as much functional organ as possible (e.g., sphincter-sparing surgery for rectal cancer, nephron-sparing partial nephrectomy, limb-salvage for bone sarcoma). |
| v. Minimum blood loss and avoidance of blood transfusion | Major blood loss → hypotension → organ hypoperfusion → postoperative organ failure. Blood transfusion → immunosuppression → loss of immune control of microscopic cancer foci → rapid recurrence. The mechanism is that transfused histocompatibility antigens induce specific immunologic non-reactivity (a form of tolerance), suppressing the host's anti-tumour immune surveillance. [1] |
Critical Concept: Blood Transfusion and Cancer Recurrence
Blood transfusion leads to immunosuppression and loss of control of microscopic foci of cancer growth, thus contributing to rapid recurrence. Loss of immune control of cancer cells is due to the transfused histocompatibility antigen which induces specific immunologic non-reactivity. [1] This is a unique and highly testable concept from this lecture. The examiners may ask why blood transfusion is avoided in cancer surgery — the answer is NOT just about fluid overload or infection, but about immunosuppression and cancer recurrence.
"Overall, a patient's survival rate is dependent on tumour stage, blood loss volume, requirement of blood transfusion, and function of the organ bearing the tumour." [1]
| Determinant | Details |
|---|---|
| Tumour stage (TNM) | Measured by the TNM staging system devised by UICC (International Union Against Cancer). T = primary tumour size/invasion, N = regional lymph node involvement, M = distant metastasis. It is the most widely used system, provides a prognostic guide, and enables comparison of treatment results between centres or methods. [1] |
| Blood loss volume | Dependent on surgeon experience, technique, and difficulty of operation. Modern techniques (laparoscopic, robotic, vascular control methods like Pringle manoeuvre) reduce blood loss. |
| Blood transfusion | As above — immunosuppressive effect increases recurrence risk. |
| Organ function | If too much organ is removed (e.g., 80% hepatectomy for liver cancer), the patient may develop organ failure (liver failure) which may shorten survival if the liver does not regenerate rapidly. [1] The liver is unique among organs in its regenerative capacity. |
"Yes, depending on the site, size and number of cancer recurrence. Some recurrence can be treated by surgery again or other modalities." [1]
Key points:
- The recurrence must be small before re-treatment is possible — this is why close surveillance is mandatory after all cancer operations [1]
- Imaging possible sites of spread (CT, MRI, PET-CT depending on cancer type) and measurement of serum tumour marker levels (e.g., CEA for colorectal, AFP for HCC, CA 19-9 for pancreatic) are the mainstay of surveillance [1]
- Examples of treatable recurrence:
"Adjuvant chemotherapy, radiotherapy and immunotherapy can reduce recurrence in some but not all patients. Because of the side effects of chemotherapy and radiotherapy, adjuvant chemotherapy should be given to the group of patients at significant risk of recurrence." [1]
Why Not Give Adjuvant Therapy to Everyone?
Adjuvant therapy has side effects (neutropenia, nausea, cardiotoxicity, radiation fibrosis, etc.). If the absolute risk of recurrence is low (e.g., Stage I colon cancer), the harm of chemotherapy outweighs the benefit. That's why we stratify patients by stage and risk features to decide who gets adjuvant therapy. For example, Stage III colon cancer (node-positive) routinely gets adjuvant chemotherapy (FOLFOX), while Stage I does not. [2][4]
| Cancer | When Adjuvant Therapy Is Indicated | Typical Regimen |
|---|---|---|
| Colon | Stage III (N+), high-risk Stage II | FOLFOX / Xelox [2][4] |
| Rectal | Stage II–III (neoadjuvant chemoRT standard) | 5-FU based + RT [2][3] |
| Breast | Most invasive cancers; depends on receptor status | Chemo ± trastuzumab ± hormonal [5] |
| Lung (NSCLC) | Stage II–III, high-risk IB | Cisplatin-based [6] |
| Gastric | T3+ or N+ | FLOT / Xelox [7] |
| Slide/Section | Key Content | Exam Relevance |
|---|---|---|
| Introduction | Surgery is the most effective method of cancer therapy currently available | Opening statement — may appear in True/False |
| Why surgery cures cancer | Removes tumour + margin + regional LN | Foundation of all cancer surgery questions |
| Measuring success | 5 metrics; hospital mortality more accurate than 30-day | Definitions commonly tested |
| 5-year OS rates | Breast 85%, Liver 60%, Colon 50%, Lung 45% | Direct recall in MCQ |
| Why not 100% | 6 reasons including haematogenous spread and iatrogenic dissemination | SAQ "list reasons" type |
| Principles of surgery | 5 principles; blood transfusion immunosuppression mechanism | Very high yield for SAQ/viva |
| Determinants of survival | TNM (UICC), blood loss, transfusion, organ function | Framework for any cancer surgery question |
| Treating recurrence | Small recurrence treatable; surveillance mandatory | Links to follow-up protocols |
| Preventing recurrence | Adjuvant therapy for high-risk patients only | Connects to site-specific lectures |
Clinical Approach: Applying Principles to Practice
- Duration and progression of symptoms
- Constitutional symptoms (weight loss, anorexia, fatigue) — suggest advanced disease
- Site-specific symptoms (e.g., change in bowel habit for colorectal, haemoptysis for lung)
- Risk factors (smoking, alcohol, family history, hepatitis B/C for HCC)
- Functional status — can the patient tolerate major surgery?
- Previous treatments (neoadjuvant therapy, prior surgery)
- Primary tumour assessment (size, fixity, relation to adjacent structures)
- Regional lymph node stations (axillary for breast, cervical for H&N, inguinal for lower limb melanoma)
- Signs of distant metastases (hepatomegaly, ascites, Virchow's node, bone tenderness)
- Organ function assessment (jaundice for liver, respiratory function for lung)
- Tissue diagnosis — biopsy (core needle, FNA, incisional, excisional, frozen section intraoperatively) [8]
- Staging — imaging (CT, MRI, PET-CT), blood markers (CEA, AFP, CA 19-9, CA-125, PSA)
- Functional assessment — organ function tests (LFT, RFT, spirometry), performance status (ECOG/Karnofsky)
- Preoperative workup — bloods, ECG, CXR, anaesthetic assessment, nutritional status
- Curative surgery — following the 5 principles above
- Neoadjuvant therapy — when downstaging improves resectability (rectal cancer, locally advanced breast, gastric)
- Adjuvant therapy — when recurrence risk is significant
- Surveillance — imaging + tumour markers at regular intervals
- Treatment of recurrence — re-resection if small/isolated; systemic therapy if widespread
- Palliative care — when cure is not possible (symptom control, QoL)
| Related Lecture | How This Lecture's Principles Apply |
|---|---|
| GC 194 – Colorectal cancer [2] | En-bloc resection, ≥5 cm margins (colon), ≥12 LN, FOLFOX adjuvant for Stage III |
| GC 181 – Breast cancer [5] | Lumpectomy with clear margins + SLNB (minimum manipulation), adjuvant chemo/hormonal/targeted |
| GC 212 – Gastric cancer [7] | D2 lymphadenectomy (LN clearance principle), gastrectomy with 5 cm gross margins |
| GC 077 – Lung cancer [6] | Lobectomy + mediastinal LN dissection, adjuvant chemo for Stage II-III |
| Advanced liver surgery | Major hepatectomy with future liver remnant assessment (organ function principle), portal vein embolization |
| GC 201 – Skin cancer | Wide local excision with appropriate margins (4-6 mm for BCC, varies for SCC/melanoma) |
| Malignant biliary obstruction | Whipple operation: radical resection + LN clearance; preop biliary drainage to optimize organ function [9] |
Exam Intelligence
| Trap | Correct Understanding |
|---|---|
| "30-day mortality is the best measure of surgical outcome" | Hospital mortality is more accurate because ICU patients can survive > 30 days before dying of surgical complications [1] |
| "Surgery can cure all cancer if you operate early enough" | False — haematogenous spread may already be present at time of surgery; surgery cannot eradicate distant metastases [1] |
| "Blood transfusion is avoided in cancer surgery only because of infection risk" | The key reason is immunosuppression leading to loss of immune control of cancer cells and rapid recurrence [1] |
| "All cancer patients should receive adjuvant chemotherapy" | Only those at significant risk of recurrence (e.g., Stage III colon, not Stage I) [1] |
| "Disease-free survival and overall survival are the same" | DFS excludes patients with recurrence; OS includes them as survivors |
| "TNM staging was devised by AJCC" | The lecture states it was devised by UICC (International Union Against Cancer) [1]. Note: AJCC collaborates with UICC, but the lecture specifically credits UICC |
| "Positive resection margins always mean the surgeon did a bad job" | Sometimes the cancer is close to indispensable viscera or blood vessels making clear margins impossible [1] |
| "Minimum manipulation" means "don't operate" | It means handle the tumour gently, ligate vessels first, avoid squeezing — not that you should avoid surgery |
- MCQ: "Which of the following is the most accurate measure of surgical outcome for cancer?" → Hospital mortality rate
- SAQ: "List 5 principles of cancer surgery" or "State 4 reasons why surgery cannot achieve 100% cure rate"
- Minicase: A patient with cancer surgery → what surveillance? What if recurrence found?
- Viva: "Why do we avoid blood transfusion in cancer surgery?" → immunosuppression mechanism
High Yield Summary
-
*Surgery is the most effective cancer therapy available
- — it removes tumour + margins + regional LN.
-
*Hospital mortality
- is a more accurate outcome measure than 30-day mortality.
-
*5-year OS after surgery
- Breast ~85%, Liver ~60%, Colon ~50%, Lung ~45%.
-
Surgery fails because of: operative mortality, pre-existing haematogenous spread, occult foci, unattainable margins, iatrogenic dissemination, and organ function loss.
-
*Five principles
- clear margins, minimum manipulation, LN clearance, preserve function, minimize blood loss.
-
*Blood transfusion causes immunosuppression
- (via transfused histocompatibility antigens inducing non-reactivity) → loss of immune control → cancer recurrence.
-
*TNM staging (UICC)
- is the universal prognostic system.
-
*Determinants of survival
- tumour stage, blood loss, transfusion requirement, organ function.
-
*Surveillance
- (imaging + tumour markers) is mandatory after all cancer operations to detect small, treatable recurrences.
-
*Adjuvant therapy
- (chemo/RT/immunotherapy) reduces recurrence but should only be given to patients at significant risk due to side effects.
Active Recall - Surgical Oncology
[1] Lecture slides: GC 202. Surgery may cure your cancer Surgical oncology - Notes.pdf [2] Senior notes: Maksim Surgery Notes.pdf (Management of colon cancer, Management of rectal cancer) [3] Senior notes: MBBS Final MB (Surgery) (Felix PY Lai).pdf (Colon cancer surgical treatment, Rectal cancer surgical treatment) [4] Senior notes: Maksim Medicine Notes.pdf (Clinical oncology - Colorectal cancer) [5] Senior notes: Ryan Ho Urogenital.pdf (Breast cancer management) [6] Senior notes: Ryan Ho Respiratory.pdf (Lung cancer surgical options) [7] Senior notes: Maksim Surgery Notes.pdf (Non-surgical treatments in CA stomach) [8] AOS material: AOS - Pathology.pdf (Frozen section indications) [9] Senior notes: Ryan Ho Fundamentals.pdf (Malignant biliary obstruction management)
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