MSI High: 30 Real Stories

30 stories match MSI high. 26 of them mention surgery.

Cancer Stories

Cindy, who was diagnosed with Stage IV Colorectal CancerColorectal Cancer

Stage IV MSI-High Colorectal Cancer: Cindy's Patient Story

Patient Info: Cindy Mette, Female | Stage IV

Biomarkers: MSI-high

Cindy’s tumor responded to the experimental Werner helicase inhibitor, with falling CEA levels and radiologic response. The response was continuing in 2025 while she remained on the clinical trial.

MD Anderson
OutcomeResponding Well
JJ, who was diagnosed with Stage IV Colorectal CancerColorectal Cancer

Stage IV MSI-High Colorectal Cancer: JJ's Patient Story

Patient Info: JJ, Male, Under 40 | Stage IV

Biomarkers: Lynch syndrome; microsatellite instability

Metastatic Site: Abdominal wall; lymph nodes throughout the body

At the latest scan, the main abdominal tumor remained stable. JJ had completed 126 rounds of chemo-immunotherapy and continued treatment every 3 weeks; small lung nodules were being watched but were not confirmed as metastases.

The Patient Story
OutcomeStable Disease / Ongoing Therapy
A patient, who was diagnosed with Stage IV Colorectal AdenocarcinomaColorectal Cancer

Stage IV MSI-H KRAS-mutant colorectal adenocarcinoma: severe pembrolizumab-associated hypercalcemia resolved with steroids and zoledronic acid

Patient Info: Anonymized, Female, 70+ | Stage IV

Biomarkers: KRAS G12xa mutation; MSI-H; BRAF wild type; NRAS wild type; PTH low-normal

Metastatic Site: liver

After the second pembrolizumab dose, severe hypercalcemia and electrolyte abnormalities resolved with high-dose glucocorticoids, zoledronic acid, and supportive care; cancer response was not yet described.

PubMed Central
OutcomeCare Ongoing
Tommy, who was diagnosed with Stage III Colorectal CancerColorectal Cancer

Stage III MSI-High Colorectal Cancer: Tommy's Survivor Story

Patient Info: Tommy Allen, Male, 50s | Stage III

Biomarkers: MSI-high; Lynch syndrome

As of November 2025, Tommy was cancer-free 5 years after pembrolizumab, ileostomy, Whipple procedure, partial colectomy, and ileostomy closure for Stage III MSI-high colon cancer with Lynch syndrome.

MD Anderson
OutcomeCancer-Free / NED
A patient, who was diagnosed with Stage IV Lung CancerLung Cancer

Stage IVA lung adenosquamous carcinoma: complete response after paclitaxel, nedaplatin, and tislelizumab

Patient Info: Anonymized, Male, 60s | Stage IV

Biomarkers: Adenosquamous lung cancer markers; PD-L1 TPS 18%; KRAS, BRAF, PIK3CA, FLT1 mutation; TMB 3.7

Metastatic Site: pleura/chest wall, cervical lymph nodes, axillary…

As of March 30, 2025, he maintained complete response with normal tumor markers, no radiologic evidence of progression or recurrence, and progression-free survival of 46.5 months after paclitaxel/nedaplatin/tislelizumab followed by maintenance tislelizumab.

PubMed Central
OutcomeCancer-Free / NED
A patient, who was diagnosed with Stage III Colorectal AdenocarcinomaColorectal Cancer

Lynch syndrome bifocal colon cancer: complete pathological remission after sintilimab

Patient Info: Anonymized, Male, 40s | Stage III

Biomarkers: Lynch-associated colon cancer with MSI-H and KRAS/NRAS/BRAF wild type; tumor markers were low or near normal.

As of April 2025, pathology after proximal colectomy showed tumor regression grade 0 with complete pathological remission, and follow-up found no recurrence or metastasis.

PubMed Central
OutcomeCancer-Free / NED
A patient, who was diagnosed with Stage III Colorectal AdenocarcinomaColorectal Cancer

Stage III MSI-H/dMMR ascending colon cancer: complete response to pembrolizumab without surgery

Patient Info: Anonymized, Female, 70+ | Stage III

Biomarkers: dMMR/MSI-H with high TMB, BRAF, BRCA2 mutation, KRAS/NRAS wild-type, HER2-negative, PD-L1-negative; Lynch testing negative.

After 10 months of pembrolizumab, PET/CT showed complete metabolic response and colonoscopy biopsies were negative for malignancy; she continued nonoperative management after declining surgery.

PubMed Central
OutcomeCancer-Free / NED
Sophie, who was diagnosed with Stage IV Colorectal CancerColorectal Cancer

Sophie: Stage IV Colorectal Cancer

Patient Info: Sophie, Female | Stage IV

Biomarkers: BRAF mutation; MSI

Metastatic Site: Liver; lymph nodes; other torso lesions

As of August 2024, Sophie had been declared cancer-free after Stage IV BRAF-mutated/MSI bowel cancer responded to nivolumab/ipilimumab-based immunotherapy, with PET imaging and liver surgery biopsy showing no cancerous cells.

The Patient Story
OutcomeCancer-Free / NED
Sophie, who was diagnosed with Stage IV Colorectal CancerColorectal Cancer

Stage IV BRAF Colorectal Cancer: Sophie's Survivor Story

Patient Info: Sophie, Female | Stage IV

Biomarkers: BRAF-mutated; MSI / microsatellite instability

Metastatic Site: liver; lymph nodes including neck

As of June 2024, Sophie had been off treatment for nearly 3 years and described herself as currently cancer-free after surgery, chemotherapy, immunotherapy, and liver surgery showing no cancer cells.

The Patient Story
OutcomeCancer-Free / NED
A patient, who was diagnosed with Stage IV Invasive Ductal CarcinomaBreast Cancer

MSI-High Metastatic Hormone-Receptor-Positive Breast Cancer Responding to Pembrolizumab

Patient Info: Anonymized, female, 40s | Stage IV

Biomarkers: ER-positive; PR-positive; HER2-negative; MSI-high; BRCA mutation-negative

Metastatic Site: bone, para-aortic lymph nodes, brain

Pembrolizumab produced marked improvement in metastatic bone and nodal disease. After 1 year it was stopped because of appetite loss; 8 months later she was symptom-free and back at work on endocrine therapy, although asymptomatic brain metastases were documented.

PubMed Central
OutcomeLiving With Cancer
Stephanie, who was diagnosed with Colorectal CancerColorectal Cancer

MSI-High Colorectal Cancer: Stephanie's Patient Story

Patient Info: Stephanie Dobson, Female, Under 40

Biomarkers: MSI-high; Lynch syndrome

The rectal tumor was shrinking on immunotherapy and early treatment-related fatigue was improving.

Dana-Farber
OutcomeResponding Well
A patient, who was diagnosed with Colorectal AdenocarcinomaColorectal Cancer

Pembrolizumab produced a complete response in unresectable dMMR colon cancer

Patient Info: Anonymized, female, 70+

Biomarkers: dMMR/MSI-H; MLH1 loss; MSH2 loss; RAS/BRAF wild type; MLH1 promoter hypermethylation

Surgery found a pathological complete response with no residual cancer in the colon or 58 lymph nodes, and follow-up showed no relapse.

PubMed Central
OutcomeCancer-Free / NED
A patient, who was diagnosed with Colorectal AdenocarcinomaColorectal Cancer

Pembrolizumab enabled complete response and surgery for unresectable dMMR colon cancer

Patient Info: Anonymized, male, 60s

Biomarkers: dMMR/MSI-H; MLH1 loss; PMS2 loss; BRAF mutation; MLH1 promoter hypermethylation

The surgical specimen showed a pathological complete response with no residual cancer and 0 of 43 lymph nodes involved, and follow-up showed no relapse.

PubMed Central
OutcomeCancer-Free / NED
A patient, who was diagnosed with Stage IV Colorectal AdenocarcinomaColorectal Cancer

Pembrolizumab and surgery for metastatic dMMR colorectal cancer with major response

Patient Info: Anonymized, female, 50s | Stage IV

Biomarkers: dMMR/MSI-H; MLH1 loss; PMS2 loss; BRAF/RAS wild type; RET::NCOA4 fusion; MLH1 promoter hypermethylation

Metastatic Site: non-regional lymph nodes

Surgery showed a major pathological response with less than 10% viable tumor. Pembrolizumab was restarted after surgery, and no relapse had been documented.

PubMed Central
OutcomeCare Ongoing
A patient, who was diagnosed with Stage IV Colorectal AdenocarcinomaColorectal Cancer

Pembrolizumab led to complete response before surgery for metastatic dMMR colon cancer

Patient Info: Anonymized, male, 70+ | Stage IV

Biomarkers: dMMR/MSI-H; MLH1 loss; PMS2 loss; BRAF mutation; heterozygous MUTYH p. pathogenic variant

Metastatic Site: liver

The 2023 liver resection showed a pathological complete response with no residual tumor, and he entered follow-up without additional therapy.

PubMed Central
OutcomeCancer-Free / NED
A patient, who was diagnosed with Stage IV Lung AdenocarcinomaLung Cancer

Stage IV enteric-type lung adenocarcinoma with EGFR mutations and MSI-high disease

Patient Info: Anonymized, male, 60s | Stage IV

Biomarkers: EGFR exon 19 deletion; acquired EGFR T790M; MSI-high; high tumor mutation burden; MLH1 mutation; pMMR; PD-L1-negative

Metastatic Site: lung, pleura

The cancer progressed through multiple targeted, chemotherapy, and immunotherapy regimens. He died about 30 months after the initial diagnosis.

PubMed Central
OutcomeIn Memory
A patient, who was diagnosed with Colorectal AdenocarcinomaColorectal Cancer

Colorectal cancer: using a blood test (ctDNA) to guide immunotherapy after surgery — Case 1

Patient Info: Anonymized, Male, 50s

Biomarkers: KRAS ; TMB 11 mutations/Mb; loss of MLH1 and PMS2; dMMR/MSI-H; germline multigene panel negative; ctDNA positive after surgery and chemotherapy

Pembrolizumab cleared ctDNA within about 3 months. After completing 1 year of immunotherapy, surveillance CT showed no evidence of disease and ctDNA remained negative.

PubMed Central
OutcomeCancer-Free / NED
A patient, who was diagnosed with Colorectal AdenocarcinomaColorectal Cancer

Colorectal cancer: using a blood test (ctDNA) to guide immunotherapy after surgery

Patient Info: Anonymized, Male, 40s

Biomarkers: dMMR/MSI-H; pathogenic germline MLH1 c.1459C>T consistent with Lynch syndrome; postoperative ctDNA rose during chemotherapy and became near-undetectable on pembrolizumab

He continued pembrolizumab with no evidence of disease on interval CT and near-undetectable ctDNA. Grade 1 thyroiditis was monitored without treatment interruption.

PubMed Central
OutcomeIn Treatment
Shannon, who was diagnosed with Stage II Colorectal CancerColorectal Cancer

Stage II MSI-High Colorectal Cancer: Shannon's Survivor Story

Patient Info: Shannon, Female, Under 40 | Stage II

Biomarkers: MSI-H; Lynch syndrome; MLH1 mutation

As of October 2023, Shannon had no recurrence described while approaching year 5 after Stage IIA colon cancer surgery and continued intensive Lynch syndrome surveillance.

The Patient Story
OutcomeCancer-Free / NED