The role of resection margin status on recurrence and selection of patients for adjuvant radiotherapy in distal cholangiocarcinoma

The management of distal cholangiocarcinoma (dCC) remains a formidable challenge, with pancreatoduodenectomy as the only potentially curative option (1). Nevertheless, high rates of recurrence and suboptimal long-term survival persist, underscoring the critical importance of properly evaluating and address risk factors in order to improve outcomes (1). In this context, the recent study published by Yun et al. (2) provides critical insights into the prognostic significance of resection margin status and elucidates the nuanced role of adjuvant radiotherapy (RT).

The assessment of surgical margins in dCC is crucial for guiding surgical and postoperative treatment (3). Unfortunately, variability in margin definitions and reporting standards persists, affecting comparability across studies and the interpretation of results (4). The literature consistently demonstrates that achieving a negative (R0) margin is associated with improved survival and lower recurrence rates, making it the primary surgical goal (1,3). However, the prognostic role of carcinoma in situ (CIS) and high-grade dysplasia (HGD) at the margin, as well as their classification as R1 or R0 remains unclear (5) while the prognostic value of low-grade dysplasia (LGD) has rarely been assessed (6). Evidence suggests that the presence of CIS or HGD at the margin confers an intermediate risk profile, whereas invasive carcinoma at the margin is linked to the poorest prognostic outcomes (5,6). The clinical significance of margin width remains debated, with some data indicating that close (≤5 mm) negative margins may not provide the same benefit as wider (>5 mm) margins, particularly in node-negative patients (7). This highlights the need for meticulous surgical technique and intraoperative margin assessment at frozen section to maximize the likelihood of achieving a true negative margin.

Yun et al. (2) provide robust evidence that resection margin status is a critical determinant of recurrence in dCC. Although margin status was not a risk factor in node-positive patients, non-clear margin (R1/dysplasia) was identified as the most powerful predictor of recurrence in node-negative patients. Furthermore, the hazard ratios for recurrence increased as the severity of dysplasia in the bile duct resection margin worsened {versus clear margin, hazard ratio (HR) [95% confidence interval (CI)]: 1.90 (0.97–3.69), P=0.060 for LGD; 2.45 (1.46–4.11), P<0.001 for HGD; and 3.11 (1.64–5.90), P<0.001 for tumor present at the margin}. Their large cohort (n=587) is notable for its detailed stratification of margin status into clear (R0), LGD, HGD, and tumor present at the margin (R1). The data are striking: among node-negative patients, those with clear margins had a 5-year cumulative recurrence rate of 42.5%, whereas rates increased to 64.3% for LGD, 74.4% for HGD, and reached 100% when tumor cells were present at the margin. In contrast, among node-positive patients, margin status did not significantly affect recurrence rates, which remained high across all groups (68.8% to 100%). These findings are consistent with and extend prior research. Recently, Kang and Jo (7) demonstrated in node-negative dCC that both close (≤5 mm) and positive margins were associated with significantly worse locoregional control and progression-free survival compared with wide margins (>5 mm). Notably, the adverse impact of close margins was nearly as severe as that of positive margins, emphasizing the need for aggressive surgical clearance whenever feasible.

Another key point of the study by Yun et al. (2) is the dichotomy between node-negative and node-positive dCC. In node-positive patients, recurrence rates are high regardless of margin status, and the benefit of local therapies such as RT is very limited. Consequently, emphasis should be placed on the prompt initiation of systemic chemotherapy, a strategy endorsed by both clinical guidelines and retrospective analyses (8,9). Conversely, in node-negative patients with non-clear margins achieving local disease control remains paramount and adjuvant RT may be most impactful (10). This distinction underscores the need for individualized, risk-adapted adjuvant strategies based on both margin and nodal status (Table 1).

In other words, lymph node positivity can diminish or even negate the survival benefit of negative margins, suggesting that tumor biology and systemic spread may outweigh the impact of local control of the malignancy in these patients. It is well established that lymph node involvement is a well-known dominant prognostic factor in dCC but the presence or absence of lymph node metastasis can be acknowledged only after final pathology review. Therefore, we fully agree with Yun et al. (2) affirming the state of the margin is the only modifiable risk factor upon which the surgeon can act to potentially enhance survival outcomes. However, we propose that surgical intervention can target both ductal and radial margins. Although the radial margin cannot be assessed intraoperatively through frozen section analysis, the surgeon can strategically plan a wide removal of the periductal tissue of the hepatoduodenal ligament en bloc with the specimen to maximize the chances of obtaining a negative radial margin as well (4,11).

Currently, the pivotal BILCAP trial (12) has shifted the paradigm of adjuvant therapy, establishing capecitabine as the new standard of care for resected biliary tract cancers. It is noteworthy that this randomized controlled trial did not specifically focus on dCC but involved stratification of primary tumor location as well as resection margin. Furthermore, although the rate of positive lymph node was similar between the study arms (capecitabine versus observation group), the BILCAP study did not categorize based on lymph node status and we should be aware that dCC shows a higher rate of lymph node metastasis than other types of cholangiocarcinoma (13). For the above reasons the role of adjuvant therapy after resection for dCC is still a topic of ongoing debate (14). The study by Yun et al. (2) showed adjuvant chemotherapy is an independent protective factor for recurrence in all dCC patients, regardless of their lymph node metastasis status.

The role of adjuvant RT in dCC has been controversial, with earlier studies yielding mixed results (10). While some large database analyses and meta-analyses have failed to demonstrate a survival benefit for adjuvant RT in unselected dCC populations, subgroup analyses consistently suggest that patients with high-risk features—especially positive margins—derive the greatest benefit (15). Yun et al. (2) provide compelling evidence indicating that node-negative patients with non-clear margins who received adjuvant RT had significantly lower 5-year recurrence rates compared with those who did not receive RT (69.5% vs. 87.5%, P=0.037). Conversely, this therapeutic advantage does not extend to node-positive patients, in whom margin status appears less prognostic and local therapies have limited impact. Currently, American Society of Clinical Oncology (ASCO) clinical practice guidelines recommend considering chemo-radiation for patients with extrahepatic cholangiocarcinoma presenting with microscopically positive margins (9).

The valuable findings of the study by Yun et al. (2) advocate for a tailored approach that emphasizes the aggressive pursuit of clear margins intraoperatively, the judicious use of adjuvant RT in node-negative patients with non-clear margins, and the prioritization of systemic therapy in node-positive cases. Moreover, the evidence highlights the need for standardized definitions of margin status and the conduct of larger, prospective studies to refine adjuvant treatment strategies. Despite these advances, several limitations remain. The majority of investigations, including the study by Yun et al. (2), are retrospective and subject to selection bias. The rarity of dCC and heterogeneity of adjuvant therapy regimens prior to the BILCAP trial (12) further complicate the interpretation and comparison of results. Lastly, the optimal sequencing and combination of chemotherapy and RT remain to be defined (10).

In summary, the evolving landscape of dCC management demands precision, both in the operating room and in postoperative decision-making. The integration of margin status and nodal involvement into the criteria for selecting adjuvant therapies represents a significant step toward improved patient prognosis.

Acknowledgments

None.

Footnote

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