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// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 1 — TITLE
// ─────────────────────────────────────────────────────────────────────────────
addTitleSlide(pres,
  "GASTRIC CARCINOMA",
  "Epidemiology  |  Pathology  |  Staging  |  Management"
);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 2 — OVERVIEW / KEY FACTS
// ─────────────────────────────────────────────────────────────────────────────
addContentSlide(pres, "Overview — Key Facts", [
  "One of the most common causes of cancer-related death worldwide",
  "Prognosis is generally poor; overall cure rates approximately 5–10% in the West",
  "Better results in Japan due to high incidence, screening programmes and high-quality surgical treatment",
  "Only curative treatment is resectional surgery",
  "Aetiology is multifactorial — environmental, dietary and genetic factors",
  "H. pylori is important in distal but NOT proximal gastric cancer",
  "Early gastric cancer is associated with high cure rates — early diagnosis is key",
  "Gastric cancer classified into intestinal type and diffuse type; diffuse type has worse prognosis",
]);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 3 — SECTION: EPIDEMIOLOGY
// ─────────────────────────────────────────────────────────────────────────────
addSectionDivider(pres, "01  EPIDEMIOLOGY", "Incidence & Global Distribution");

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 4 — INCIDENCE
// ─────────────────────────────────────────────────────────────────────────────
addTwoColumnSlide(pres, "Incidence & Global Distribution",
  "Incidence per 100,000/year",
  [
    "UK: ~15 per 100,000 per year",
    "USA: ~10 per 100,000 per year",
    "Eastern Europe: ~40 per 100,000 per year",
    "Japan: ~70 per 100,000 per year",
    "Parts of China: even higher rates",
    "Clearly an environmental disease based on epidemiology",
    "Men more affected than women",
    "Incidence increases with age",
  ],
  "Changing Trends in the West",
  [
    "Overall incidence falling ~1% per year",
    "Fall exclusively in body and distal gastric cancer",
    "Proximal stomach / GOJ cancers are increasing",
    "Distal cancer: more common in low socioeconomic groups",
    "Proximal cancer: affects higher socioeconomic groups",
    "Proximal cancer not associated with H. pylori",
    "Proximal cancer linked to obesity",
    "Japan: distal cancer still predominates",
  ]
);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 5 — AETIOLOGY
// ─────────────────────────────────────────────────────────────────────────────
addSectionDivider(pres, "02  AETIOLOGY", "Risk Factors & Predisposing Conditions");

addTwoColumnSlide(pres, "Aetiology of Gastric Cancer",
  "Established Risk Factors",
  [
    "H. pylori infection (body & distal stomach)",
    "Pernicious anaemia and gastric atrophy",
    "Gastric adenomatous polyps",
    "Previous peptic ulcer surgery (Billroth II / Pólya gastrectomy) — ~4× average risk",
    "Bile reflux and intestinal metaplasia",
    "Cigarette smoking",
    "Industrial dust inhalation",
    "Diet high in salt and N-nitroso compounds",
    "Deficiency of dietary antioxidants",
  ],
  "Proximal Gastric Cancer",
  [
    "Aetiology remains an enigma",
    "NOT associated with H. pylori",
    "Associated with obesity",
    "Associated with higher socioeconomic status",
    "Genetic factors important but not fully elucidated",
    "Japanese immigrants to USA show declining risk — confirms environmental role",
  ]
);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 6 — SECTION: PATHOLOGY
// ─────────────────────────────────────────────────────────────────────────────
addSectionDivider(pres, "03  PATHOLOGY", "Macroscopic & Microscopic Classification");

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 7 — LAUREN CLASSIFICATION
// ─────────────────────────────────────────────────────────────────────────────
addTwoColumnSlide(pres, "Lauren Classification of Gastric Cancer",
  "Intestinal Type",
  [
    "More common; more favourable prognosis",
    "Gland-forming, cohesive tumour cells",
    "Associated with intestinal metaplasia and H. pylori",
    "More common in older males",
    "Arises from precancerous lesion sequence: gastritis → atrophy → metaplasia → dysplasia",
    "Tends to spread haematogenously to liver",
    "Better defined margins",
  ],
  "Diffuse Type",
  [
    "Less common; worse prognosis",
    "Poorly cohesive signet-ring cells",
    "Spreads via submucosal and subserosal lymphatic plexus",
    "Penetrates gastric wall at an early stage",
    "Not linked to H. pylori or intestinal metaplasia",
    "More common in younger patients and women",
    "Linitis plastica — extreme form of diffuse type",
  ]
);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 8 — BORRMANN CLASSIFICATION
// ─────────────────────────────────────────────────────────────────────────────
addTableSlide(pres, "Borrmann Classification — Advanced Gastric Cancer",
  ["Type", "Description", "Key Feature"],
  [
    ["Type I", "Polypoid", "Protruding mass, well-demarcated"],
    ["Type II", "Ulcerating", "Ulcer with raised, well-defined margins"],
    ["Type III", "Infiltrating / Ulcerating", "Ulcer with ill-defined, infiltrating margins"],
    ["Type IV", "Infiltrating (Linitis Plastica)", "Diffuse infiltration — 'leather bottle stomach'"],
  ]
);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 9 — EARLY GASTRIC CANCER
// ─────────────────────────────────────────────────────────────────────────────
addContentSlide(pres, "Early Gastric Cancer (EGC)", [
  "Defined as cancer confined to mucosa or submucosa, regardless of lymph node status",
  "Type I — Protruded: raised polypoid lesion above mucosal surface",
  "Type IIa — Superficial elevated: slightly raised, flat lesion",
  "Type IIb — Flat: barely distinguishable from surrounding mucosa",
  "Type IIc — Superficial depressed: slightly depressed below mucosal level",
  "Type III — Excavated: deep ulcerated lesion",
  "Associated with high cure rates following resection",
  "Common in Japan due to active endoscopic screening programmes",
  "No specific clinical features distinguish it from benign dyspepsia — high clinical suspicion required",
]);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 10 — SECTION: MOLECULAR PATHOLOGY
// ─────────────────────────────────────────────────────────────────────────────
addSectionDivider(pres, "04  MOLECULAR PATHOLOGY", "Genetic & Molecular Alterations");

addContentSlide(pres, "Molecular Pathology of Gastric Cancer", [
  "HER2 overexpression in approximately 15–20% of gastric cancers — targetable with trastuzumab",
  "Chromosomal instability (CIN): most common molecular subtype — aneuploidy and somatic copy number alterations",
  "Microsatellite instability (MSI): defective mismatch repair; more favourable prognosis",
  "Epstein–Barr virus (EBV)-associated gastric cancer: ~10% of cases",
  "Genomically stable (GS) subtype: enriched for CDH1 mutations and diffuse histology",
  "TP53 mutations common in intestinal type",
  "CDH1 (E-cadherin) mutations in hereditary diffuse gastric cancer",
  "VEGF, EGFR and MET pathways implicated — targets for novel therapies",
  "PD-L1 expression relevant for checkpoint immunotherapy eligibility",
]);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 11 — SECTION: SPREAD
// ─────────────────────────────────────────────────────────────────────────────
addSectionDivider(pres, "05  SPREAD", "Routes of Metastasis");

addTwoColumnSlide(pres, "Spread of Gastric Carcinoma",
  "Direct & Lymphatic Spread",
  [
    "Direct: penetrates muscularis → serosa → adjacent organs (pancreas, colon, liver)",
    "Diffuse type penetrates gastric wall early via submucosal/subserosal lymphatics",
    "Lymphatic spread: by permeation and emboli to node tiers",
    "Troisier's sign — supraclavicular lymph node involvement",
    "Nodal involvement does NOT imply systemic dissemination (unlike breast cancer)",
  ],
  "Blood-borne & Transcoelomic",
  [
    "Haematogenous spread: first to liver, then lung, bone",
    "Blood-borne metastases uncommon in absence of nodal disease",
    "Transperitoneal spread: once tumour reaches serosa",
    "Peritoneal seedlings indicate incurability",
    "Krukenberg tumour — transcoelomic spread to ovaries",
    "Blumer's shelf — transcoelomic deposits in pouch of Douglas (palpable on rectal exam)",
  ]
);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 12 — CLINICAL FEATURES
// ─────────────────────────────────────────────────────────────────────────────
addSectionDivider(pres, "06  CLINICAL FEATURES", "Presentation & Physical Signs");

addTwoColumnSlide(pres, "Clinical Features of Gastric Cancer",
  "Symptoms",
  [
    "Early cancer: no specific features — mimics benign dyspepsia",
    "Advanced cancer: early satiety, bloating, distension",
    "Vomiting (especially with pyloric involvement → gastric outlet obstruction)",
    "Dysphagia (proximal tumours / GOJ involvement)",
    "Iron deficiency anaemia (occult bleeding)",
    "Profound weight loss",
    "Epigastric fullness and pain",
    "Paraneoplastic: Trousseau's sign — thrombophlebitis / DVT",
  ],
  "Physical Signs",
  [
    "Epigastric mass (advanced disease)",
    "Hepatomegaly (liver metastases)",
    "Troisier's sign — Virchow's node (left supraclavicular)",
    "Sister Mary Joseph nodule — periumbilical metastasis",
    "Krukenberg tumour — bilateral ovarian masses",
    "Blumer's shelf on rectal examination",
    "Ascites (peritoneal involvement)",
    "Jaundice (hepatic / biliary involvement)",
  ]
);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 13 — SITE
// ─────────────────────────────────────────────────────────────────────────────
addContentSlide(pres, "Site of Gastric Cancer", [
  "Proximal stomach is now the most common site in the West",
  "~60% of upper GI malignancies occur in proximity to the gastro-oesophageal junction (GOJ)",
  "Adenocarcinoma at the GOJ has doubled in incidence in the UK over 30 years",
  "High prevalence of proximal cancer NOT seen in Japan — distal cancer still predominates in Japan and most of the world",
  "Proximal cancer = higher socioeconomic groups, obesity, not H. pylori",
  "Distal (antral) cancer = lower socioeconomic groups, H. pylori-related",
]);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 14 — SECTION: INVESTIGATION
// ─────────────────────────────────────────────────────────────────────────────
addSectionDivider(pres, "07  INVESTIGATION & STAGING", "Diagnosis and Staging Workup");

addTwoColumnSlide(pres, "Investigation of Gastric Cancer",
  "Endoscopy & Biopsy",
  [
    "Upper GI endoscopy: gold standard for diagnosis",
    "Multiple biopsies from lesion — minimum 8 biopsies recommended",
    "Brush cytology increases diagnostic yield",
    "Endoscopic ultrasound (EUS): best for T and N staging; identifies wall layer invasion",
    "EUS-guided FNA for suspicious nodes",
  ],
  "Staging Investigations",
  [
    "CT chest, abdomen and pelvis with IV contrast — assess resectability and distant metastases",
    "Staging laparoscopy: detects peritoneal disease missed by CT in up to 30%",
    "Peritoneal washings for cytology",
    "PET-CT: useful in equivocal cases",
    "HER2 testing of tumour biopsy (FISH / IHC) — guides targeted therapy",
    "Full blood count, LFTs, tumour markers (CEA, CA19-9)",
  ]
);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 15 — UICC TNM STAGING TABLE
// ─────────────────────────────────────────────────────────────────────────────
addTableSlide(pres, "UICC/TNM Staging — Gastric Cancer (8th Edition)",
  ["Category", "Description"],
  [
    ["T1a", "Invasion of lamina propria or muscularis mucosae"],
    ["T1b", "Invasion of submucosa"],
    ["T2", "Invasion of muscularis propria"],
    ["T3", "Tumour involves subserosa"],
    ["T4a", "Tumour perforates serosa (visceral peritoneum)"],
    ["T4b", "Tumour invades adjacent structures"],
    ["N0 / N1 / N2 / N3", "0 / 1–2 / 3–6 / ≥7 regional lymph nodes involved"],
    ["M0 / M1", "No distant metastasis / Distant metastasis present"],
  ]
);

// Stage grouping
addTableSlide(pres, "Stage Grouping — Gastric Cancer (UICC 8th Edition)",
  ["Stage", "T", "N", "M"],
  [
    ["IA", "T1", "N0", "M0"],
    ["IB", "T1–T2", "N0–N1", "M0"],
    ["IIA", "T1–T3", "N0–N2", "M0"],
    ["IIB", "T1–T4a", "N0–N3", "M0"],
    ["IIIA", "T2–T4a", "N1–N3a", "M0"],
    ["IIIB", "T1–T4b", "N0–N3b", "M0"],
    ["IIIC", "T3–T4b", "N3", "M0"],
    ["IV", "Any T", "Any N", "M1"],
  ]
);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 17 — SECTION: SURGICAL TREATMENT
// ─────────────────────────────────────────────────────────────────────────────
addSectionDivider(pres, "08  SURGICAL TREATMENT", "Curative & Palliative Surgery");

addTwoColumnSlide(pres, "Surgical Management — Gastric Cancer",
  "Curative Resection",
  [
    "Only curative treatment is resectional surgery",
    "Total gastrectomy (TG): tumours of the body / proximal stomach",
    "Subtotal gastrectomy: distal tumours — survival equivalent to TG with less morbidity",
    "Oesophagogastrectomy (Ivor Lewis): for GOJ / proximal tumours",
    "Minimum 5 cm proximal and distal resection margins required",
    "D2 lymphadenectomy: removal of second-tier nodes around principal arterial trunks — recommended for curative intent",
    "D1: removal of immediately perigastric nodes only",
    "D2 vs D1: may provide survival advantage; standard in Japan and specialist Western centres",
  ],
  "Reconstruction",
  [
    "Roux-en-Y oesophagojejunostomy after total gastrectomy",
    "Billroth I (gastroduodenostomy) after subtotal gastrectomy",
    "Billroth II (gastrojejunostomy): alternative for subtotal",
    "Palliative: gastrojejunostomy bypass for GOO",
    "Palliative: endoscopic stenting for GOO or GOJ obstruction",
    "Palliative: PEJ / PEG for nutritional support",
  ]
);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 18 — CHEMO / ADJUVANT THERAPY
// ─────────────────────────────────────────────────────────────────────────────
addSectionDivider(pres, "09  NON-SURGICAL TREATMENT", "Chemotherapy & Targeted Therapy");

addTwoColumnSlide(pres, "Chemotherapy & Targeted Therapy",
  "Perioperative / Adjuvant Chemotherapy",
  [
    "Chemotherapy improves survival in both resectable (perioperative) and advanced disease",
    "FLOT (fluorouracil, leucovorin, oxaliplatin, docetaxel): preferred perioperative regime",
    "ECF / ECX (epirubicin, cisplatin, 5-FU / capecitabine): historical standard",
    "Pre-operative chemo can downstage tumour and increase R0 resection rate",
    "Post-operative chemo / chemoradiotherapy also used",
  ],
  "Palliative & Targeted",
  [
    "Palliative chemotherapy: platinum-containing triplet combinations or FLOT",
    "Second-line: docetaxel-containing combinations",
    "Trastuzumab (Herceptin): approved for HER2-positive metastatic gastric cancer",
    "HER2-positive: <20% of patients; ~4-month absolute survival benefit",
    "Trastuzumab approved in UK and EU for HER2-positive metastatic disease",
    "Immune checkpoint inhibitors (PD-1/PD-L1): emerging role",
    "Radiotherapy: palliative role for painful bone metastases",
  ]
);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 19 — PATTERN OF RELAPSE
// ─────────────────────────────────────────────────────────────────────────────
addContentSlide(pres, "Pattern of Relapse After Radical Gastrectomy", [
  "Most common site of relapse: gastric bed — inadequate extirpation of primary tumour",
  "Widespread nodal and intraperitoneal metastases",
  "Distant nodal metastases",
  "Liver metastases",
  "Lung and bone metastases usually only occur after liver metastases are established",
  "Systemic chemotherapy: key component of management in relapsed / metastatic disease",
  "Re-resection: rarely feasible; only in highly selected cases",
]);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 20 — PROGNOSIS
// ─────────────────────────────────────────────────────────────────────────────
addTableSlide(pres, "Prognosis by Stage & Histological Type",
  ["Factor", "Better Prognosis", "Worse Prognosis"],
  [
    ["Stage", "Stage I (EGC)", "Stage III–IV (advanced)"],
    ["Lauren Type", "Intestinal type", "Diffuse type / Linitis plastica"],
    ["Lymph node status", "N0 — node negative", "N3b — ≥16 nodes involved"],
    ["Resection margins", "R0 (clear)", "R1/R2 (involved)"],
    ["Lymphadenectomy", "D2 (specialist centres)", "D1 or less"],
    ["HER2 status", "HER2+ (trastuzumab eligible)", "MSS, non-targetable"],
    ["Geography", "Japan (active screening)", "Western countries (late presentation)"],
    ["Overall 5-yr survival", "EGC: >90%", "Advanced: ~10–20%"],
  ]
);

// ─────────────────────────────────────────────────────────────────────────────
// SLIDE 21 — CONCLUSION
// ─────────────────────────────────────────────────────────────────────────────
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