When PMP Returns: New Research Identifies Risk Factors for Recurrence After Surgery
Kazi, Mufaddal & Reddy, Kaliki & Sharma, Ankit & Souza, Ashwin & Saklani, Avanish. (2026). Patterns and Predictors of Relapse Following Cytoreductive Surgery for Pseudomyxoma Peritonei. Journal of Surgical Oncology. 10.1002/jso.70445.
A new study published in the Journal of Surgical Oncology offers important insights into why pseudomyxoma peritonei (PMP) may return following cytoreductive surgery (CRS), where recurrence is most likely to occur, and which patients may face a higher risk.
recurrence is an important part of long-term care. While cytoreductive surgery, often combined with hyperthermic intraperitoneal chemotherapy (HIPEC), can provide meaningful long-term disease control, recurrence remains a concern.
This research helps physicians better understand which factors may influence recurrence and how follow-up care might be tailored to individual patients.
What Did the Researchers Study?
Researchers examined the medical records of 204 patients who underwent cytoreductive surgery for appendix-related PMP at a single treatment center between 2016 and 2025.
The study focused on three important questions:
How frequently does PMP return after surgery?
Where in the abdomen does recurrence most commonly occur?
Which factors are associated with a higher likelihood of recurrence, particularly within the first year?
Approximately 92% of patients also received HIPEC, a treatment that delivers heated chemotherapy directly into the abdominal cavity during surgery.
Patients were followed for a median of approximately three years.
What Did the Study Find?
1. Recurrence occurred in approximately 44% of patients.
Of the 204 patients, 89 experienced disease recurrence during the follow-up period.
At three years, the estimated progression-free survival rate was 50.2%, meaning approximately half of patients were alive without disease progression. The estimated overall survival rate at three years was 75.6%.
These findings demonstrate that although recurrence is relatively common, many patients experience meaningful periods of disease control following treatment.
2. PMP most often returned within the abdominal cavity.
Researchers found that recurrence occurred predominantly within the peritoneal cavity, the space containing the abdominal organs.
The most common locations were:
Pelvis: Approximately 25% of recurrences.
Small bowel and mesentery: Approximately 25% of recurrences. The mesentery is the tissue that supports and connects the intestines within the abdomen.
Identifying these common sites may help specialists understand patterns of recurrence and inform postoperative monitoring.
3. Tumor grade was an important predictor of recurrence.
The study found that the microscopic characteristics of PMP tumors, known as histology, were strongly associated with recurrence risk.
Compared with patients who had acellular mucin (mucin without identifiable tumor cells), those with low-grade, high-grade, or signet-ring cell PMP had higher risks of disease progression.
High-grade and signet-ring cell disease were associated with particularly elevated risks.
This reinforces the importance of accurate pathology evaluation and understanding the specific classification of PMP.
4. The completeness of surgery mattered.
One of the strongest findings involved how much visible disease remained after cytoreductive surgery.
Surgeons use a Completeness of Cytoreduction (CC) score to describe the amount of disease remaining after surgery.
Patients who achieved complete or near-complete cytoreduction (CC-0 or CC-1) generally experienced better outcomes than those with greater amounts of residual disease (CC-2 or CC-3).
In this study, approximately 89% of patients achieved CC-0 or CC-1 cytoreduction.
This highlights the importance of evaluation and treatment by surgical teams experienced in managing peritoneal surface malignancies.
5. Certain factors predicted recurrence within the first year.
Researchers also examined early recurrence, defined as disease returning within 12 months of surgery.
Among the 204 patients, 34 (17%) experienced early recurrence.
Two factors were particularly important:
High-grade tumor histology.
Incomplete cytoreduction, with significant disease remaining after surgery (CC-2 or
CC-3).
Patients with these characteristics had a higher likelihood of early recurrence, suggesting they may benefit from particularly individualized postoperative follow-up.
What Does This Mean for Patients?
This research emphasizes that PMP is not the same for every patient. Tumor biology, surgical outcomes, and individual clinical circumstances all contribute to the likelihood of recurrence.
For patients and caregivers, several important messages emerge.
Understanding your pathology matters. Knowing whether PMP is classified as low-grade, high-grade, or another subtype can help patients have more informed conversations about prognosis and follow-up care.
Specialized surgical expertise is important. The association between complete cytoreduction and better outcomes reinforces the value of seeking evaluation from specialists experienced in treating PMP and other peritoneal surface malignancies.
Long-term follow-up remains essential. Even after successful surgery, patients need an individualized surveillance plan. Follow-up may involve imaging, tumor markers, and clinical evaluation based on the patient's circumstances.
Recurrence does not necessarily mean there are no further treatment options. For carefully selected patients, additional treatment, including repeat cytoreductive surgery, may be considered. Decisions depend on factors such as the location and extent of recurrence, tumor biology, overall health, and previous treatments.
Important Study Limitations
This was a retrospective study involving patients treated at a single institution. Its findings identify associations between clinical factors and recurrence but cannot establish that any particular factor directly causes recurrence.
The study also does not establish an ideal surveillance schedule or prove that more frequent monitoring or repeat surgery improves survival. Additional research involving larger, diverse patient populations is needed to refine individualized follow-up strategies.
The Alliance's Perspective
For patients facing pseudomyxoma peritonei, the possibility of recurrence can create uncertainty even after successful treatment. This study offers valuable information that may help patients and their care teams better understand risk and make informed decisions about long-term care.
The findings reinforce an important message: PMP treatment and follow-up should be individualized, and specialized expertise matters.
A patient's pathology, surgical results, and unique circumstances all help shape the path forward. Importantly, an increased risk of recurrence does not mean recurrence is inevitable.
The Abdominal Cancers Alliance encourages patients to seek care from specialists experienced in treating PMP, understand their pathology and surgical results, and maintain ongoing communication with their medical team.
Knowledge, access to specialized care, and continued support can help patients feel better prepared for the road ahead.
