Evolution of Initial Treatment for Desmoid Tumors

Introduction: Desmoid tumors (DTs) are rare, fibroblastic cell proliferations that can exhibit locally aggressive behavior but lack metastatic potential. Initial management has traditionally involved upfront resection; however, contemporary guidelines and expert panels have increasingly advocated for prioritizing active surveillance strategies.

Methods: A single-institution, retrospective chart review identified all patients diagnosed with a primary DT at any site from 2007 to 2020. The primary outcome was the initial management strategy over time. Secondary outcomes included treatment-free survival (TFS) and time to treatment (TTT) for those undergoing active surveillance, as well as recurrence-free survival (RFS) and time to recurrence for those undergoing resection.

Results: Overall, 103 patients were included, with 68% female and a median follow-up of 44 months [24-74]. The most common tumor locations included the abdominal wall (27%), intra-abdominal/mesenteric (25%), chest wall (19%), and extremity (10%). Initial management included resection (60%), systemic therapy (20%), active surveillance (18%), and cryoablation (2%). Rates of surgical resection significantly decreased (p < 0.001) over time, from 69.6% prior to 2018 to 29.2% after 2018. For those treated with upfront resection, 5-year RFS was 41.2%, and for patients undergoing initial active surveillance, TFS was 66.7% at 2 years, with a median TTT of 4 months [4-10]. Conclusions: This single-institution cohort at a tertiary medical center spanning over a decade demonstrates the transition to active surveillance for initial management of DTs, and highlights salient metrics in the era of surveillance. This trend mirrors recommended treatment strategies by expert panels and consensus guidelines.

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Background: Aggressive fibromatosis (AF), also known as desmoid tumor or desmoid-type fibromatosis, is a rare soft tissue neoplasm that can occur in almost any part of the body. Although it is a benign disease, AF is aggressive and infiltrative and has a high recurrence rate after surgery. Common sites for intra-abdominal AF are the small bowel mesentery, retroperitoneum, and pelvis. AF in the colon is extremely rare.

Case summary: Here, we report the first case of sigmoid colon AF, which was accidentally discovered in a 27-year-old woman during laparoscopic myomectomy. Computed tomography confirmed a slightly enhanced mass in the sigmoid colon. Subsequent colonoscopy did not reveal a mass in the colonic lumen, but a suspected external compress was found in the sigmoid colon. Surgical disease involving a gastrointestinal stromal tumor was suspected. The patient underwent laparoscopic exploration, and sigmoidectomy with a negative margin was performed to excise the mass. Postoperative immunohistochemistry revealed that the mass was an AF. The patient recovered well and was recurrence-free at the 30-month follow-up without adjuvant therapy.

Conclusion: AF should be considered in the differential diagnosis of subepithelial colon masses. Radical resection alone can achieve good outcomes.

Importance  Desmoid tumor (DT) is a rare and locally aggressive monoclonal, fibroblastic proliferation characterized by a variable and often unpredictable clinical course. Previously, surgery was the standard primary treatment modality; however, within the past decade, a paradigm shift toward less-invasive management has been introduced and an effort to harmonize the strategy among clinicians has been made. To update the 2020 global evidence-based consensus guideline on the management of patients with DT, the Desmoid Tumor Working Group convened a 1-day consensus meeting in Milan, Italy, on June 30, 2023, under the auspices of the European Reference Network on Rare Adult Solid Cancers and Sarcoma Patient Advocacy Global Network, the Desmoid Foundation Italy, and the Desmoid Tumor Research Foundation. The meeting brought together over 90 adult and pediatric sarcoma experts from different disciplines as well as patients and patient advocates from around the world.

Observations  The 2023 update of the global evidence-based consensus guideline focused on the positioning of local therapies alongside surgery and radiotherapy in the treatment algorithm as well as the positioning of the newest class of medical agents, such as γ-secretase inhibitors. Literature searches of MEDLINE and Embase databases were performed for English-language randomized clinical trials (RCTs) of systemic therapies to obtain data to support the consensus recommendations. Of the 18 full-text articles retrieved, only 4 articles met the inclusion criteria. The 2023 consensus guideline is informed by a number of new aspects, including data for local ablative therapies such as cryotherapy; other indications for surgery; and the γ-secretase inhibitor nirogacestat, the first representative of the newest class of medical agents and first approved drug for DT. Management of DT is complex and should be carried out exclusively in designated DT referral centers equipped with a multidisciplinary tumor board. Selection of the appropriate strategy should consider DT-related symptoms, associated risks, tumor location, disease morbidities, available treatment options, and preferences of individual patients.

Conclusions and Relevance  The therapeutic armamentarium of DT therapy is continually expanding. It is imperative to carefully select the management strategy for each patient with DT to optimize tumor control and enhance quality of life.

Objective: To investigate the clinicopathological and genetic characteristics of neuromuscular choristoma-associated desmoid type fibromatosis (NMC-DF). Methods: The clinical morphological and immunohistochemical features of 7 NMC-DF cases diagnosed from January 2013 to January 2023 in Beijing Jishuitan Hospital were retrospectively analyzed. A series of neuromuscular choristoma and neuromuscular choristoma-associated desmoid type fibromatosis were evaluated for CTNNB1 mutations, and hotspot mutations for CTNNB1 were tested in 4 NMC-DF cases using Sanger sequencing. Results: The tumors were collected from 3 females and 4 males, aged 1 to 22 years (mean 7.1 years), involving the sciatic nerve (n=4), brachial plexus (n=2) or multiple nerves (n=1). The course of the disease spanned from 3 months to 10 years. Two cases were recurrent tumors. All the 7 NMC cases showed endoneurial intercalation of mature skeletal muscle fibers among the peripheral nerve fascicles, and the histologic features of the NMC-DF were strikingly similar to the conventional desmoid-type fibromatosis. By immunohistochemistry, all NMC and NMC-DF cases showed aberrant nuclear staining of β-catenin (7/7), the muscle cells in NMC were intensely immunoreactive for desmin, and the admixed nerve fibers were highlighted by NF and S-100 (7/7). Four NMC and NMC-DF had CTNNB1 mutations, 3 c.121A>G (p.T41A) and 1 c.134C>T (p.S45F). Follow-up of the 7 cases, ranging from 22 to 78 months, showed tumor recurrence in 2 patients at 3 and 8 months respectively after the first surgical resection, of which 1 patient underwent above-knee amputation. No recurrence occurred in other cases with tumor excision and neurological reconstruction surgery. There was no metastasis occurred in the 7 cases. Conclusions: NMC is a rare congenital lesion with differentiated mature skeletal muscle tissue found in peripheral nerve fascicles, and approximately 80% of patients with NMC develop a soft tissue fibromatosis. CTNNB1 mutation in the Wnt signaling pathway may be involved in the pathogenesis of NMC and NMC-DF, and S45F mutations seems to have a higher risk of disease progression.

Background & aims: Desmoid tumours (DT) are an important cause of morbidity and mortality in patients with familial adenomatous polyposis (FAP). DT development might be related to the type and approach of colectomy. We aimed to compare DT development after colectomy with ileorectal anastomosis (IRA) and proctocolectomy with ileal pouch-anal anastomosis (IPAA).

Methods: We performed an international historical cohort study in FAP patients who underwent IRA or IPAA between 1961 and 2020. The primary outcome was the incidence of abdominal DT (either mesenteric, retroperitoneal or abdominal wall). Patients with a DT diagnosis before or at colectomy were excluded. Time to DT was considered censored at an eventual secondary proctectomy after IRA. We used multivariable Cox regression modelling to adjust for potential confounders.

Results: We analysed data from 852 patients: 514 after IRA and 338 after IPAA (median follow-up 21 and 16 years, respectively). DTs were diagnosed in 64 IRA patients (12%) and 66 IPAA patients (20%). The cumulative DT incidence at 5 and 10 years was 7.5% and 9.3% after open IRA and 4.7% and 10.9% after laparoscopic IRA. These estimates were 13.6% and 15.4% after open IPAA and 8.4% and 10.0% after laparoscopic IPAA. The post-operative risk was significantly higher after IPAA (p < 0.01) in multivariable analysis, while approach did not significantly influence the risk. Conclusions: The risk of developing an abdominal DT was found to be significantly higher after IPAA than after IRA. Postoperative DT risk should be taken into account when choosing between IRA and IPAA in FAP.