CANCER DIAGNOSIS AND STAGING:
UNDERSTANDING YOUR REPORTS

A cancer diagnosis is not a single event — it is a structured sequence of investigations. Understanding each step helps patients identify where the process may be incomplete and what is still needed before treatment begins.

1. 1

   Step 1: Presenting Symptom and Initial Assessment

   A symptom, abnormal finding, or blood test prompts clinical assessment. The most common error at this stage is concluding the workup too early — treating a lump as benign without biopsy, or attributing abdominal symptoms to gastritis without endoscopy.

2. 2

   Step 2: Imaging to Identify and Characterise the Abnormality

   CT, MRI, ultrasound, or PET-CT localises the suspected tumour, assesses its size and relationship to adjacent structures, and looks for regional or distant spread. Imaging guides biopsy planning but cannot replace tissue diagnosis.

3. 3

   Step 3: Biopsy — Obtaining Tissue

   The biopsy removes a sample of abnormal tissue for microscopic examination. No cancer treatment should begin without a tissue diagnosis. Core needle biopsy is preferred over FNA for most solid tumours — it preserves tissue architecture for IHC and molecular testing.

4. 4

   Step 4: Pathology — Confirming the Diagnosis

   The pathologist confirms cancer type, grade, IHC markers, and margin status (if surgical). The pathology report is the most important document in the diagnostic package — everything else is built on it.

5. 5

   Step 5: Staging — Determining the Extent of Disease

   Systematic staging investigations — specific to the tumour type — determine T, N, and M categories and the overall stage group. Accurate staging is the foundation of treatment planning.

6. 6

   Step 6: Molecular Profiling — Understanding the Cancer's Biology

   NGS, IHC, MSI, TMB, and other molecular tests identify targetable alterations and predictive biomarkers. This step most commonly separates expert oncology centres from non-specialist facilities — and is the step most often missing in incomplete workups.

The pathology report is the cancer's birth certificate — it confirms existence, identity, and character. Written for clinicians, its key components can be understood by any patient with the right guide.

“The pathology report is the foundation on which the entire treatment plan is built — every clinical decision follows from it.”

• Histological Type and Grade

  Confirms the cancer's cell type (adenocarcinoma, squamous cell, large B-cell lymphoma, etc.) and grade (1/2/3 or low/intermediate/high). Grade reflects how abnormal the cells look — higher grade = more aggressive behaviour.

• Immunohistochemistry (IHC) Results

  Antibodies applied to the slide detect specific proteins — ER, PR, HER2 for breast; TTF-1 for lung; CD20 for lymphoma. Results are positive (+) or negative (−) with a score for intensity. IHC determines treatment eligibility (e.g., HER2+ mandates trastuzumab).

• Ki-67 Proliferation Index

  Percentage of tumour cells actively dividing. Low Ki-67 (<10%) = slow-growing. High Ki-67 (>30%) = aggressive tumour needing more intensive treatment. Critically important for neuroendocrine tumours and breast cancer treatment planning.

• Surgical Margins (R Classification)

  R0 = clear margins (no tumour at cut edge) — the surgical goal. R1 = microscopic tumour at margin — adjuvant radiation typically required. R2 = visible tumour left behind — curative intent not achieved. A close margin (<1–2mm) requires tumour-type-specific management.

The type of biopsy determines how much tissue is available, which tests can be performed, and whether a repeat biopsy will be needed. Understanding which biopsy you had — and whether it was sufficient — is an essential diagnostic awareness check.

TNM is the universal language of cancer staging. T describes the primary tumour, N describes regional lymph node involvement, and M describes distant metastasis. The three categories are combined into a Stage Group (I–IV) using tumour-specific grouping tables.

Radiology reports describe imaging findings in technical language that can be opaque even to non-specialist physicians. The key terms below appear repeatedly across cancer staging and treatment response reports.

• CT Scan: Key Terms

  Hypodense = darker than surrounding tissue (cyst, necrosis, liver met). Enhancement = contrast uptake indicating live tumour. Lymphadenopathy = enlarged lymph nodes >1cm short-axis. Size reported as longest diameter for RECIST. "Infiltration of" = tumour extending into adjacent structure.

• MRI: When It Adds More Than CT

  Superior for brain/spinal cord tumours, liver (HCC vs benign), rectal cancer (mesorectal fascia involvement), and breast MRI staging. DWI (diffusion-weighted imaging) identifies highly cellular tumour areas. T2-weighted images show anatomy; T1 post-contrast shows enhancement.

• PET-CT: SUV and FDG Uptake

  SUVmax = maximum metabolic activity within a lesion; values >2.5 typically abnormal. FDG-avid = metabolically active, consistent with malignancy. Non-avid tumours (mucinous CRC, diffuse gastric, prostate, brain) can be underestimated by PET. CMR (complete metabolic response) = no residual FDG activity after treatment.

• RECIST 1.1: How Treatment Response Is Measured

  Up to 5 target lesions measured at baseline. Response: CR = all lesions gone; PR = ≥30% decrease in sum of longest diameters; PD = ≥20% increase or new lesion; SD = neither. RECIST is the standard for clinical trial endpoints and treatment response assessment in solid tumours.

Tumour markers are used for staging, treatment response monitoring, and recurrence surveillance — not for primary diagnosis in isolation. Trend over time matters far more than any single value.

An NGS report is one of the most information-dense documents in oncology. Understanding its structure and the classification of variants enables patients to identify clinically actionable findings and ask the right questions.

• Pathogenic Variant

  A mutation definitively known to drive cancer or activate oncogenic signalling. These are the most important findings — they are the direct targets for specific drugs. Examples: EGFR exon 19 deletion (lung, targets osimertinib), BRAF V600E (melanoma/CRC, targets vemurafenib + cobimetinib), BRCA2 frameshift (ovarian, targets olaparib).

• Variant of Uncertain Significance (VUS)

  A variant detected whose clinical significance is not yet established. VUS findings are reported for completeness but should not be used to select or exclude treatments without additional evidence. The proportion of VUS findings decreases as molecular databases grow — a VUS today may be reclassified in 12–18 months.

• Gene Fusions and Copy Number Alterations

  Fusions (ALK, RET, ROS1, NTRK) are critically important driver alterations — many have approved targeted drugs. Amplification (HER2, MET, EGFR) indicates excess gene copies, often driving resistance or targeted therapy eligibility. Both are missed by single-gene testing — only NGS reliably detects them.

• TMB and MSI: The Immunotherapy Predictors

  TMB (tumour mutational burden, mut/Mb) — high TMB (>10 mut/Mb) predicts pembrolizumab response across any solid tumour type (tumour-agnostic FDA approval). MSI-H (microsatellite instability-high) or dMMR (mismatch repair deficient) predicts response to checkpoint inhibitors across all solid tumour types — the most important tumour-agnostic biomarker in oncology.

For any cancer diagnosis, the following nine questions should be answerable from the medical records before treatment begins. Missing any element may result in an incorrect stage, a missed treatment target, or an unnecessary treatment.

1. 1

   Tissue Biopsy Confirmed

   Is there a pathology report confirming cancer from a tissue biopsy — not from imaging, clinical examination, or a blood test alone? Tissue diagnosis is mandatory before any cancer treatment.

2. 2

   Histological Type and Grade Specified

   Does the pathology report state the exact histological subtype (not just "carcinoma") and the tumour grade? Subtype determines which systemic therapy protocols apply.

3. 3

   Essential IHC Panel Completed

   Have the IHC markers specific to your tumour type been performed? (ER/PR/HER2/Ki-67 for breast; TTF-1/napsin A/p40 for lung; CD20/CD3/Ki-67 for lymphoma.) Missing IHC markers may mean missing targeted therapy eligibility.

4. 4

   Molecular Biomarkers Tested (Cancer-Specific)

   Have all the essential molecular tests for your specific cancer type been done? (EGFR/ALK/ROS1/KRAS/MSI/TMB for NSCLC; BRCA1/2/HRD for ovarian; KRAS/NRAS/BRAF/MSI for colorectal; HER2/MSI for gastric.) Untested biomarkers = untried treatments.

5. 5

   Complete Staging Imaging Performed

   Have all the required staging investigations for your cancer type been performed? (e.g., staging laparoscopy for locally advanced gastric cancer; bone scan or PSMA-PET for prostate; brain MRI for NSCLC with driver mutation.) Incomplete staging leads to incorrect stage and wrong treatment intent.

6. 6

   TNM Stage Formally Assigned

   Has a formal TNM stage (T, N, M categories and overall Stage Group) been documented in the clinical record? Stage underpins every treatment recommendation.

7. 7

   Multidisciplinary Tumour Board Review

   Has the case been discussed at an MDT/tumour board including surgical oncology, medical oncology, radiation oncology, radiology, and pathology? MDT review reduces treatment errors and improves outcomes.

8. 8

   Written Treatment Plan Documented

   Is there a written treatment plan specifying the proposed therapy, the evidence basis, and alternatives considered? A verbal plan without documentation is not sufficient.

9. 9

   Action: What to Do When Gaps Are Identified

   If a missing molecular test could change the treatment plan — request it before starting therapy. If staging investigations are incomplete — insist on completion. If no tumour board review has occurred — request one. If uncertain — seek a second opinion from a specialist oncology centre.

Liquid biopsy (ctDNA from blood) has become standard practice in several clinical scenarios but cannot replace tissue biopsy for primary diagnosis. Understanding when each is appropriate prevents both missed opportunities and misapplication.

Data illustrating the clinical impact of complete molecular profiling and accurate staging on treatment outcomes.

• 30–40%NSCLC Patients with Actionable MutationsEGFR, ALK, ROS1, NTRK, RET, MET — each requiring a different targeted drug. All missed without comprehensive NGS.
• ~5%All Solid Tumours That Are MSI-HMSI-H is a tumour-agnostic biomarker for pembrolizumab — applicable across all cancer types regardless of origin.
• 20–30%Gastric Cancer Patients with Occult Peritoneal MetsMissed on CT staging; detectable only by staging laparoscopy — the most commonly omitted staging investigation.
• 1 in 3Cancer Patients with Incomplete Molecular WorkupEstimated proportion of advanced cancer patients who begin treatment without complete biomarker testing — missing potentially superior treatment options.

A well-organised, complete medical record package is the single most important practical task before seeking a second opinion or travelling for treatment. Disorganised records delay review and risk missing critical information.

• Category 1 — All Pathology Reports

  All biopsy and surgical pathology reports in chronological order. Note whether original glass slides and FFPE tissue blocks are available at the pathology department — specialist centres may require these for review or additional IHC/NGS.

• Category 2 — Imaging Reports + DICOM Files

  All CT, MRI, PET-CT, and ultrasound reports. Critically: digital DICOM image files on USB or secure cloud link — not printed films or JPEG photos. DICOM files allow the reviewing radiologist to measure lesions, scroll through slices, and apply RECIST criteria independently.

• Category 3 — Blood Tests and Tumour Markers

  All laboratory reports including CBC, metabolic panel, and tumour markers (CEA, CA19-9, AFP, PSA, CA-125, LDH) at baseline and all follow-up time points. Marker trends over time are clinically more valuable than any single value.

• Category 4 — Molecular and Genomic Reports

  NGS panel reports, IHC results, FISH results, PCR-based mutation testing (EGFR, KRAS, MSI), PD-L1 staining, germline genetic test results. If no molecular testing has been performed, note this explicitly — it is often the most actionable gap.

• Category 5 — Treatment Records

  Chemotherapy, targeted therapy, immunotherapy, and radiation records showing specific drugs, doses, cycles, dates, and any dose reductions or interruptions. Surgery operative reports and anaesthetic notes.

• Category 6 — Clinical Correspondence + Case Summary

  Specialist letters, clinic notes, discharge summaries in chronological order. Add a 1–2 page plain-language case summary: age, gender, date of diagnosis, cancer type, stage, treatments received, current status, and specific question for the reviewing specialist.

Frequently Asked Questions