Tumour board: operation planning, imatinib-resistant liver metastases of gastric GIST

Question to the board

Which lesions should be treated now, in which order and by which technique, and how are imatinib and regorafenib managed around the procedures?

Lesions

Volumetry is AI-assisted on consensus segmentations with inferred segments; non-tumour parenchyma 1.41 L; remnant after right hemihepatectomy + S1 ≈ 0.69–0.78 L (49–53 %); after both targets in one stage ≈ S4 only (9–20 %). Surgical volumetry must replace these figures.

Questions for the board (in order of dependency)

1. Operate now? Does the unresolved cytology (category V; AUS on review) stop surgery, or is it settled by peritoneal inspection and frozen-section washings at the start of surgery? [alternatives within days: repeat tap with cell block at CSD if fluid reaccumulates; second-look laparoscopy. Note: frozen section applies to nodules; DOG1/CD117 on a cell block is a post-operative result] ^[2,3]
   OPINION Dr Fedorov’s position (16.10.2026, opinion): he considers the earlier category V finding over-diagnosis against the background of the cancer diagnosis (“they overdid it”; presumably the first report); malignant cells would have been on all slides.
2. Order and staging. Right hemihepatectomy (R1 with the S8 lesion) first or L1 first; one stage or two; and how is R1 — the 1.2 L right-lobe mass with FDG-active wall plaques — handled: resection only, or is drainage/aspiration an option? [surgeon’s order changed 18.09 ^[D190] → 09.10 OPINION; remnant estimates in the collapsed block; no published GIST series on drainage] ^[4,14]
   OPINION Dr Fedorov’s position (16.10.2026, opinion): right hemihepatectomy first: the right-lobe lesion has a fluid component that could rupture (an emergency, then carcinomatosis, after which no surgery would be radical); most of the right lobe is non-functioning tumour, so little healthy liver is lost and he sees no high risk of liver failure; the left-lobe lesion at a second stage, because one stage would leave too little functional parenchyma. Drainage or aspiration of R1 was not mentioned.
3. L1 technique and operator. For L1 — 54 mL on the 23.09.2026 consensus model (4.9 × 3.9 × 5.9 cm), biopsy-proven viable GIST (05.10.2026) ^[D195], 0–1 mm from the left portal branch and the left bile duct — which option is feasible here, where and by whom: resection of the left lateral section (segments II–III), irreversible electroporation (NanoKnife), histotripsy (HistoSonics), SBRT, or transarterial treatment (DEB-TACE/TARE) of the segment II/III feeding artery? [thermal ablation declined by Dr Korshak, 10–11.09.2026 OPINION; written: thermal ablation of the left-lobe focus “judged technically inadvisable” (discharge summary, 13.10.2026 ^[D201]) FACT; conditional per ULIS ^[D188]; June 2026: 42 × 36 mm (Israeli reading ^[D77]). Access / cost: TARE from about EUR 40,000, not performed in Ukraine; histotripsy at HCA Healthcare UK (London) costs from £37,500 for the treatment itself, plus £500 initial review (oncologist + MDT), about £250 per clinician per visit and about £100 for the radiologist’s imaging review (e-mail reply of 11.09.2026; no quote for her case issued)] ^[5,6,7,8]
   OPINION Dr Fedorov’s position (16.10.2026, opinion): no local treatment of L1 now: for embolisation it is unclear what to embolise; ablation works for small lesions and here would be only partial; if L1 grows before stage two, palliative ablation or chemoembolisation, most likely not radical.
4. Same-session targets. Are the S8 dome lesion (79 mL) with its new 14 × 23 mm active focus, the R1 wall plaques and the calcified gastric primary ^[D195] addressed in the same operation, or left or treated separately? ^[9,10]
   OPINION Dr Fedorov’s position (16.10.2026, opinion): the tumour board recommended removing the gastric tumour; in the same operation if a local resection is enough, the extent decided at intra-operative revision (20.10.2026: otherwise left for the second stage).
5. Operator, venue, window. Who operates, where, and in which window (from 19.10.2026? OPINION), and is the contrast CT with volumetry done before the first operation (last contrast study 19.06.2026 ^[D70])? ^[14]
   OPINION Dr Fedorov’s position (16.10.2026, opinion): the operation is possible “this Wednesday” if the patient agrees (INTERPRETATION 21.10.2026, computed from the call date); the written tumour-board conclusion was due on 19.10.2026.
6. Imatinib and regorafenib. Imatinib stopped 20.10.2026 before surgery: confirm the restart date after the operation; regorafenib not allowed now: timing of regorafenib or an alternative after the local step? [imatinib stopped 20.10.2026 before surgery, restart a few days after the operation, timing to be discussed; regorafenib dispensed 30.09.2026 ^[D76], not started, not allowed currently (family report, 20.10.2026); label: regorafenib ≥ 2 weeks after major surgery and wound healing] ^[11,12,13]
   OPINION Dr Fedorov’s position (16.10.2026, opinion): imatinib “not now”; after the operation she returns to it once her condition allows — consistent with the stop on 20.10.2026 before surgery (family report). Regorafenib was not discussed.
7. PRES safety. After haemorrhagic PRES (2023) ^[D22]: peri-operative blood-pressure target, anaesthesia plan, and which VEGFR-active drugs (sunitinib, regorafenib) to avoid around surgery and SBRT? ^[12]
8. Response check. Which check after each step — contrast CT at 4–6 weeks, PET-CT at 3 months, repeat ctDNA — and who orders and reads it? ^[15]
   OPINION Dr Fedorov’s position (16.10.2026, opinion): one CT about two weeks after surgery to assess liver regeneration; no more frequent imaging because of the contrast and radiation load.
9. Next systemic line or trial. Which drug or trial would cover both resistance clones (KIT exon 13 V654A and exon 18 A829P) at the lowest neurovascular risk after her PRES — sunitinib, regorafenib, ripretinib, velzatinib (StrateGIST 3), bezuclastinib + sunitinib or pimitespib — and at what point: now, or only after local control fails? [regorafenib dispensed 30.09.2026, not started, held because surgery is expected soon (family report, 14.10.2026); sunitinib prescribed 30.07 and 08.09.2026, not started; each later TKI line gives a shorter time to the next progression with more toxicity; blood-pressure safeguards needed; full comparison in the drug table] ^[1]
   OPINION Dr Fedorov’s position (16.10.2026, opinion): no systemic therapy other than imatinib was discussed.
10. Immune- and antibody-based options. Is any immune- or antibody-based approach a candidate for her now or alongside local treatment — the KIT-targeted antibody–drug conjugate trial (NN3201, NCT06805825), a checkpoint inhibitor with regorafenib, or an intratumoral or cell-therapy trial — and under what conditions? [evidence weak and mostly preclinical; TMB 3–4.8 Muts/Mb, MSS; OpenEvidence review, sections 13–16]
    OPINION Dr Fedorov’s position (16.10.2026, opinion): immunotherapy is not indicated in her case; immunomodulators are of unproven efficacy; on in-vivo CAR-T: “it would be great if something like that appeared”.

Needed within days (owner): operation protocol of 05.10.2026 (Shalimov) · contrast CT/MRI with volumetry and arterial phase (surgeon/radiology) · coagulation, CBC, biochemistry, ECOG, height/weight (treating team) · anaesthesia review with blood-pressure plan and SVC/port status · cell-block cytology if fluid reaccumulates (CSD) · EGD done 02.10.2026 (oesophagus not described; family report 20.10.2026: a cold with a mild sore throat in those days) · histology of the colon neoplasias (colonoscopy 02.10.2026).

Prepared as a discussion document; not a treatment recommendation. Supporting questions (Priority 2), research items (Priority 3), decision map, consultants’ statements and the literature retrieved live on 14.10.2026 are in the case page (hcl14.github.io/anastasia, section ‘Questions for the tumour board’).