Lead: In January 2017 in Maine, Diane Davis was found to have advanced ovarian cancer after months of unexplained illness. Standard surgery and chemotherapy failed when a new pelvic mass and lymph node spread appeared midway through treatment. Molecular testing identified Lynch syndrome, a hereditary DNA-repair disorder, which opened the option of immunotherapy. After receiving pembrolizumab, her disease regressed rapidly and she has remained in remission six years later.
Key takeaways
- Diane Davis underwent exploratory surgery in January 2017 that revealed a softball-sized ovarian tumor that had spread to other organs.
- After three cycles of chemotherapy a new pelvic mass appeared and cancer had also involved lymph nodes — recurrence unusually rapid and ominous for ovarian cancer.
- Molecular profiling of the tumor identified Lynch syndrome, a hereditary defect in DNA-repair proteins linked to higher mutation burden.
- Following FDA approval for certain biomarker-defined patients in June 2017, Davis began pembrolizumab every three weeks and saw the pelvic mass disappear after two treatments.
- Davis remained on immunotherapy for two years and, as of November 8, 2025, is in complete remission with ongoing surveillance.
- Lynch syndrome carries roughly a 50% chance of being passed to offspring; multiple family members tested positive and early screening caught a large precancerous polyp in Davis’s daughter at age 29.
Background
Ovarian cancer often presents late because symptoms are vague; Davis reported months of worsening nausea and back pain before scans and a colonoscopy failed to explain her illness. In early 2017, a gynecologic oncologist at MaineHealth Maine Medical Center, Dr. Christopher Darus, performed exploratory surgery and removed a large ovarian mass that had already spread. Rapid recurrence during chemotherapy is unusual and historically signals a poor prognosis.
Lynch syndrome — also called hereditary nonpolyposis colorectal cancer (HNPCC) in older literature — results from inherited defects in mismatch repair proteins that correct DNA copying errors. Tumors arising in Lynch patients commonly carry many mutations, which can make them more visible to the immune system but also allow cancers to progress when immune checkpoints are engaged. The recognition of biomarker-driven immunotherapy in the mid-2010s reframed treatment options for these patients.
Main event
After the surgery and initial chemotherapy, clinicians noted a rapidly growing pelvic mass and lymph node involvement, an outcome Dr. Darus described as highly concerning because early recurrence typically predicts short survival. Faced with limited standard options, he sent tumor tissue for molecular testing to look for actionable biomarkers. Laboratory analysis revealed a pattern consistent with Lynch syndrome, clarifying why multiple relatives had developed cancer.
Armed with that molecular diagnosis, the care team considered checkpoint inhibition to reactivate anti-tumor immunity. Pembrolizumab — a PD-1 inhibitor — had just received authorization for use in certain patients with mismatch-repair deficiency or high microsatellite instability. Davis started infusions every three weeks; within two cycles imaging showed the pelvic lesion had vanished and lymph node disease was regressing.
Davis continued on immunotherapy for two years under regular surveillance. Her family then underwent cascade testing: her son tested negative, her daughter tested positive and received earlier-than-usual colonoscopic surveillance that found a large precancerous polyp removed without complication. Davis’s father and uncle, who died of cancer in their 60s, are now believed to have carried the same inherited variant tracing back to her paternal grandfather.
Analysis & implications
This case highlights how tumor molecular profiling can convert a terminal-appearing diagnosis into a treatable condition by revealing an underlying hereditary syndrome. Lynch-associated tumors frequently harbor dozens to hundreds of mutations, increasing the likelihood that checkpoint inhibitors will elicit a meaningful immune response. For an individual patient, that can translate into rapid radiographic response and durable remission, as seen here.
At the population level, identifying hereditary cancer syndromes allows preventive measures that reduce morbidity and mortality. Cascade testing enables relatives at 50% genetic risk to start earlier surveillance, as Davis’s daughter did with a colonoscopy at age 29 that detected a large precancerous lesion. That intervention likely averted progression to invasive cancer.
Clinically, the case underscores the need to consider germline and somatic testing when family history or unusual tumor behavior appears. While not every patient with Lynch syndrome will respond to immunotherapy, the approval of tissue-agnostic indications for drugs like pembrolizumab has broadened options for biomarker-positive patients and shifted decision-making toward precision medicine.
Comparison & data
| Metric | Typical recurrent ovarian cancer | Lynch-associated, immunotherapy-treated case |
|---|---|---|
| Recurrence timeframe | Often >6 months for better prognosis | Recurrence within chemotherapy course (weeks–months) |
| Expected short-term survival (if very early relapse) | Often <2 years | Durable remission observed at 6+ years |
| Response to checkpoint inhibitor | Variable; depends on biomarkers | Rapid radiographic regression after 2 cycles |
The table contrasts broad averages with this case outcome. While early recurrence generally predicts shorter survival, a high tumor mutation burden from mismatch-repair deficiency can increase responsiveness to PD-1 blockade. These comparisons are illustrative, not predictive for every patient.
Reactions & quotes
“It was devastating at first, but learning the diagnosis gave a path forward,”
Diane Davis, patient
Context: Davis described relief that a molecular diagnosis explained her family history and opened a treatment she had not previously been offered.
“Lynch syndrome creates a high mutation load that can make some tumors more susceptible to immune-based therapy,”
Dr. Paul Oberstein, medical oncologist, NYU Langone
Context: Dr. Oberstein, who studies mismatch-repair–deficient cancers, emphasized why those tumors may respond to checkpoint inhibitors while noting not all patients benefit.
“We sent tissue for molecular profiling when standard therapy failed, and the result changed everything,”
Dr. Christopher Darus, gynecologic oncologist, MaineHealth Maine Medical Center
Context: Dr. Darus described the diagnostic and therapeutic pivot from conventional chemotherapy to a biomarker-driven immunotherapy approach.
Unconfirmed
- The precise pathogenic variant in the Davis family has not been publicly disclosed and thus the specific gene (e.g., MLH1 vs MSH2) is not confirmed in reporting.
- Records linking the paternal grandfather, father and uncle decisively to the same inherited variant are based on family history reconstruction and not full public genetic documentation.
Bottom line
This case demonstrates how integrating molecular diagnostics with evolving therapies can change outcomes in cancers once considered effectively incurable. A hereditary diagnosis explained an atypical family pattern and tumor behavior and enabled use of an approved immunotherapy that produced a rapid, durable response in this patient.
For clinicians, the lesson is to consider early molecular and germline testing when cancer presents with unusual features or strong family clustering. For families, cascade testing paired with appropriate surveillance can prevent or detect cancers at a treatable stage — turning a single diagnosis into an opportunity for multigenerational risk reduction.