Accurate cancer diagnosis is the foundation of every treatment decision. From the first clinical suspicion to surgical planning — the quality of investigation determines the quality of care. Understand every test, scan, and biopsy used to diagnose, stage, and plan treatment for cancer.
No cancer treatment should begin without a confirmed tissue diagnosis and accurate staging. Investigations serve three distinct purposes in oncology: to detect and diagnose cancer, to determine its extent (staging), and to guide the choice and sequence of treatment.
Cancer investigations have evolved dramatically. Today, a single blood sample can reveal tumour mutations. A PET-CT scan can detect cancer spread to a lymph node just 8mm in size. Liquid biopsies can identify cancer-specific DNA in the bloodstream. Modern oncology is as much a science of diagnosis as it is of treatment.
As a surgical oncologist, Dr. Gore reviews all investigations before operating — and frequently requests additional or repeat tests when findings are incomplete, discordant, or insufficient for surgical planning. Operating on inadequate information is one of the most preventable causes of poor outcomes in cancer surgery.
In my practice, I review every scan personally — not just the report. I want to see the exact tumour margins, the vascular relationship, the nodal stations involved. A report that says "tumour seen" is not enough to plan a Whipple's operation or a total laryngectomy.
I also see many patients who have had incomplete investigations — missing a PET-CT, or biopsy from the wrong site, or no molecular testing. Before proceeding, we get the right tests done. It delays treatment by days, but saves months of wrong treatment.
— Dr. Vinod T. Gore, MBBS MS FAIS FIAGES FARIS (Edin)Cancer diagnosis follows a systematic sequence — from clinical suspicion to a treatment-ready plan. Each step builds on the last.
Patient presents with symptoms or is picked up on routine cancer screening
Full clinical assessment — history, examination, performance status evaluation
CT / MRI / Ultrasound / PET-CT to visualise the tumour and assess spread
Tissue sampling — FNAC, core needle, excision — for histological diagnosis
IHC, NGS, FISH, MSI, TMB — for targeted therapy eligibility and prognosis
Multidisciplinary tumour board discussion → personalised treatment plan
Imaging is the cornerstone of cancer staging. Each modality has distinct strengths — and the right combination gives the surgeon a complete picture of the disease.
PET-CT (Positron Emission Tomography combined with CT) is the most powerful staging tool in oncology. It combines the metabolic information of PET (cancer cells consume more glucose — they "light up" with the radiotracer FDG) with the anatomical precision of CT — in a single scan of the entire body.
Contrast-enhanced CT is the primary staging tool for most solid tumours. Provides detailed cross-sectional anatomy — tumour size, vascular involvement, nodal disease, organ metastases. Essential before every major cancer operation.
Superior soft tissue resolution — preferred for rectal cancer staging (MRI pelvis), brain tumours, liver lesions, breast (MRI breast), sarcoma, and spinal cord involvement. No radiation. Longer scan time.
First-line investigation for abdominal and pelvic symptoms. Guides biopsy procedures (USG-guided FNAC/core biopsy). Used for thyroid, breast, axillary nodal assessment, liver, and superficial soft tissue lesions. Widely available, no radiation.
Nuclear medicine scan using Technetium-99m to detect bone metastases — particularly useful in breast, prostate, lung, and thyroid cancers. PET-CT has largely replaced bone scans in centres where it is available.
Combines endoscopy with ultrasound — placed inside the oesophagus or stomach to image tumours and surrounding structures with high precision. Gold standard for staging oesophageal, gastric, pancreatic, and rectal cancers. Can biopsy lymph nodes simultaneously.
No treatment should begin without histological (tissue) proof of cancer. Imaging shows where cancer is — biopsy tells us exactly what it is, its grade, and its molecular characteristics. The type of biopsy chosen affects both diagnostic accuracy and subsequent surgical planning.
A fine needle (22–25G) is passed into the lump and cells are aspirated for cytological examination. Quick, minimally invasive, done under local anaesthesia. Gives cytology — cell type only, not tissue architecture. Usually the first step for thyroid, salivary gland, lymph node, and superficial lumps.
A wider bore needle extracts a core of tissue — providing histological diagnosis with tissue architecture preserved. Allows grading, receptor testing (ER/PR/HER2 in breast cancer), and molecular analysis. Done under USG or CT guidance. The preferred biopsy for most solid tumours.
Surgical removal of the entire lesion (excision) or a representative sample (incision/punch biopsy). Provides maximum tissue for diagnosis. Planned carefully — the biopsy incision must be placed so it can be excised in continuity with the definitive surgery. A badly placed biopsy incision can compromise curative surgery.
Biopsy taken during upper GI endoscopy, colonoscopy, bronchoscopy, or cystoscopy — directly from the mucosal surface of the tumour. The standard approach for GI tract, lung, and bladder cancers. Multiple biopsies improve diagnostic yield.
Detection of circulating tumour DNA (ctDNA) or circulating tumour cells (CTCs) from a blood sample. A rapidly advancing technique — used for early detection, monitoring treatment response, detecting resistance mutations, and surveillance for recurrence without repeated tissue biopsies.
Trephine needle extraction of bone marrow from the posterior iliac crest — to assess marrow involvement in haematological malignancies (lymphoma, leukaemia, myeloma) and occasionally in solid tumours with suspected marrow metastases.
Tumour markers are proteins or substances produced by cancer cells or by the body in response to cancer. They help in diagnosis, monitoring treatment response, and detecting recurrence — but are rarely diagnostic alone and must always be interpreted in clinical context.
| Tumour Marker | Associated Cancers | Primary Use | Important Note |
|---|---|---|---|
| CEA (Carcinoembryonic Antigen) | ColorectalGastricPancreaticLung | Post-operative monitoring for colorectal cancer recurrence; assessing chemotherapy response | Not diagnostic — elevated in smokers, liver disease |
| CA-125 | OvarianEndometrialPeritoneal | Ovarian cancer monitoring — response to chemotherapy and surveillance for recurrence | Elevated in endometriosis, fibroids, liver disease |
| CA 19-9 | PancreaticBiliaryGastric | Pancreatic cancer assessment; monitoring surgical resectability after neoadjuvant treatment | Not produced in Lewis antigen-negative patients (~10%) |
| PSA (Prostate Specific Antigen) | Prostate Cancer | Screening, diagnosis, monitoring after surgery or radiotherapy; PSA velocity predicts aggressiveness | Elevated in BPH, prostatitis — not specific to cancer |
| AFP (Alpha-Fetoprotein) | Hepatocellular Ca.Germ Cell Tumours | Hepatocellular carcinoma diagnosis and monitoring; testicular germ cell tumour staging and follow-up | Elevated in hepatitis, cirrhosis, pregnancy |
| Beta-hCG | Germ Cell TumoursChoriocarcinoma | Diagnosis and monitoring of testicular cancer and gestational trophoblastic disease | Always elevated in pregnancy |
| Thyroglobulin (Tg) | Differentiated Thyroid Ca. | Post-thyroidectomy surveillance — rising Tg indicates recurrence of papillary or follicular thyroid cancer | Only valid after total thyroidectomy and RAI ablation |
| Calcitonin | Medullary Thyroid Ca. | Diagnosis of MTC; post-operative monitoring; screen family members in hereditary MTC (RET mutation) | Very specific — elevated only in MTC and C-cell hyperplasia |
| LDH (Lactate Dehydrogenase) | LymphomaGerm CellMelanoma | Prognostic marker — elevated LDH correlates with high tumour burden and poorer prognosis in several cancers | Non-specific — elevated in many non-cancer conditions |
Modern cancer diagnosis goes beyond "what type of cancer" — molecular testing answers "what is driving this cancer" and "which targeted drug will work." These tests are now standard in most major cancers.
Detects specific proteins in tumour tissue using antibody staining. Used to subtype tumours (ER/PR/HER2 in breast cancer), determine cell of origin in undifferentiated tumours, and assess predictive markers like PD-L1 for immunotherapy eligibility.
ER · PR · HER2 · PD-L1 · Ki-67Comprehensive genomic profiling — analyses hundreds of cancer-related genes simultaneously. Identifies actionable mutations (EGFR, ALK, KRAS, BRCA, RET, BRAF), calculates TMB (tumour mutational burden), and assesses MSI status — guiding targeted and immunotherapy selection.
EGFR · ALK · KRAS · BRCA · TMB · MSIDetects gene amplifications, deletions, and translocations using fluorescent probes. Standard test for HER2 amplification in breast and gastric cancer (when IHC is equivocal), ALK rearrangement in lung cancer, and BCR-ABL in leukaemia.
HER2 · ALK · ROS1 · BCR-ABLTests for microsatellite instability (MSI-H) and mismatch repair deficiency (dMMR) — the single most important predictive biomarker for checkpoint inhibitor immunotherapy. MSI-H is a tumour-agnostic indication for Pembrolizumab regardless of cancer type.
PCR · IHC (MLH1, MSH2, MSH6, PMS2)Examination of tumour tissue under the microscope — establishes cell type, grade (differentiation), lymphovascular invasion, perineural invasion, and resection margin status. The definitive report after surgical excision guides adjuvant treatment decisions.
Grade · LVI · PNI · Margin Status · pTNMThe universal staging system for solid tumours — T (tumour size/depth), N (nodal involvement), M (distant metastases). Pathological TNM (pTNM) after surgery is the gold standard. Clinical staging (cTNM) is based on pre-operative investigations. Staging drives treatment protocols and prognosis.
T1 → T4 · N0 → N3 · M0 / M1Cancer screening detects cancer before symptoms develop — when it is most curable. Every cancer caught at Stage I is more likely to be cured with surgery alone than the same cancer found at Stage III or IV.
Breast cancer is the most common cancer in Indian women. Early detection through regular screening reduces mortality by up to 30%.
Cervical cancer is nearly 100% preventable with regular screening and HPV vaccination. The most successful cancer screening programme when implemented.
Colorectal cancer develops from polyps over 10–15 years — colonoscopy can remove polyps before they become cancer, genuinely preventing the disease.
India has one of the highest rates of oral cancer globally — strongly linked to tobacco (bidi, cigarette, smokeless) and areca nut/gutka use. Highly curable when detected early.
Thyroid nodules are extremely common — 95% are benign. Screening identifies which nodules carry malignancy risk and require biopsy or surgery.
Lung cancer is the leading cause of cancer death globally. Low-dose CT (LDCT) screening in high-risk smokers has shown 20–39% reduction in lung cancer mortality.
These symptoms do not always mean cancer — but they should never be ignored or self-treated for more than 2 weeks. Early evaluation by an oncologist saves lives.
Blood in urine, stools, sputum, nipple discharge, or between periods — warrants prompt investigation.
Loss of >5% body weight over 6 months without dieting or illness — a classic cancer alarm symptom.
Any new lump in the neck, axilla, groin, breast, or abdomen that is growing, painless, or hard in consistency.
Any ulcer in the mouth, tongue, or skin that does not heal in 3 weeks — must be biopsied to exclude malignancy.
Persistent hoarse voice > 3 weeks — could indicate laryngeal or thyroid cancer, or recurrent laryngeal nerve involvement.
Progressive dysphagia — especially to solids first, then liquids — is the hallmark of oesophageal or pharyngeal cancer.
Yellow discolouration of skin and eyes in a patient over 40 — without obvious cause — must be investigated for pancreatic, biliary, or liver cancer.
Persistent altered bowel habits, rectal bleeding, or mucus in stools for >4 weeks — especially over age 40 — must be investigated with colonoscopy.
A surgical oncologist does not simply read investigation reports — they personally interpret every scan, correlate findings with clinical examination, identify gaps, and ensure the investigation workup is complete before any surgical decision is made.
If you have a concerning symptom, an abnormal report, or want a complete cancer workup review — book a consultation with Dr. Gore. A surgical oncologist's review of your investigations may change your diagnosis, staging, or treatment plan.