Management of Clinically Involved Lateral Lymph Node Metastasis in Locally Advanced Rectal Cancer: A Radiation Dose Escalation Study

Simultaneous integrated boost intensity-modulated radiation therapy targeting clinically involved extramesorectal lymph nodes in locally advanced rectal cancer: A retrospective study

AIM

Consensus is lacking regarding the management of extramesorectal lymph nodes (EMLN) in rectal cancer. Using simultaneous integrated boost intensity-modulated radiation therapy (SIB-IMRT), we targeted involved EMLN and reserved lateral pelvic lymph nodal dissection (LPLND) for nonresponders. The primary aim of this work was to determine the proportion of patients who avoided LPLND and to establish the pathological EMLN positivity rate.

METHOD

Consecutive patients with rectal cancer with suspicious EMLN [short axis dimension (SAD) ≥ 7 mm], receiving SIB-IMRT as part of neoadjuvant chemoradiotherapy and subsequently undergoing total mesorectal excision (TME) or watch-and-wait, were included. Our primary objective was to determine the proportion of patients with a good nodal response (EMLN SAD < 5 mm) who were spared LPLND. The 3-year locoregional relapse rate, distant metastasis-free survival (DMFS) and overall survival (OS) were also assessed.

RESULTS

Of the 61 patients studied, 38 (62.3%) responded well to SIB-IMRT. In this group, 32 patients underwent TME alone and six were observed as per watch-and-wait. The remaining 23 (37.7%) patients with persistent EMLN received TME with LPLND. On pathological evaluation, 7 (30.4%) patients had positive nodes while 16 (69.6%) were negative. At a median follow-up of 32 months (95% CI 23.3-40.7 months), 10 (16.4%) patients developed distant metastases while none had local or pelvic relapse. The resultant 3-year DMFS and OS for the whole cohort were 84.4% and 95.1%, respectively. Overall, 5/61 (8.2%) patients encountered radiation-induced toxicity of grade 3 or above and 8/55 (14.5%) patients had severe postoperative complications.

CONCLUSION

SIB-IMRT targeting EMLN followed by selective LPLND exhibits excellent oncological outcomes. While patients responding to SIB-IMRT safely avoid LPLND, the potential for increased morbidity in nonresponders must be considered.

Outcomes and failure patterns after chemoradiotherapy for locally advanced rectal cancer with positive lateral pelvic lymph nodes: a propensity score-matched analysis

PURPOSE

This study aimed to use propensity score matching (PSM) to explore the long-term outcomes and failure patterns in locally advanced rectal cancer (LARC) patients with positive versus negative lateral pelvic lymph node (LPLN).

MATERIALS AND METHODS

Patients with LARC were retrospectively divided into LPLN-positive and LPLN-negative groups. Clinical characteristics were compared between the groups using the chi-square test. PSM was applied to balance these differences. Progression-free survival (PFS) and overall survival (OS), and local-regional recurrence (LRR) and distant metastasis (DM) rates were compared between the groups using the Kaplan-Meier method and log-rank tests.

RESULTS

A total of 651 LARC patients were included, 160 (24.6%) of whom had positive LPLN and 491 (75.4%) had negative LPLN. Before PSM, the LPLN-positive group had higher rates of lower location (53.1% vs. 43.0%, P = 0.025), T4 stage (37.5% vs. 23.2%, P = 0.002), mesorectal fascia (MRF)-positive (53.9% vs. 35.4%, P < 0.001) and extramural venous invasion (EMVI)-positive (51.2% vs. 27.2%, P < 0.001) disease than the LPLN-negative group. After PSM, there were 114 patients for each group along with the balanced clinical factors, and both groups had comparable surgery, pathologic complete response (pCR), and ypN stage rates. The median follow-up was 45.9 months, 3-year OS (88.3% vs. 92.1%, P = 0.276) and LRR (5.7% vs. 2.8%, P = 0.172) rates were comparable between LPLN-positive and LPLN-negative groups. Meanwhile, despite no statistical difference, 3-year PFS (78.8% vs. 85.9%, P = 0.065) and DM (20.4% vs. 13.3%, P = 0.061) rates slightly differed between the groups. 45 patients were diagnosed with DM, 11 (39.3%) LPLN-positive and 3 (17.6%) LPLN-negative patients were diagnosed with oligometastases (P = 0.109).

CONCLUSIONS

Our study indicates that for LPLN-positive patients, there is a tendency of worse PFS and DM than LPLN-negative patients, and for this group patients, large samples are needed to further confirm our conclusion.

Coverage of Lateral Lymph Nodes in Rectal Cancer Patients with Routine Radiation Therapy Practice and Associated Locoregional Recurrence Rates

PURPOSE

Involved internal iliac and obturator lateral lymph nodes (LLNs) are a known risk factor for the occurrence of ipsilateral local recurrences (LLR) in rectal cancer. This study examined coverage of LLNs with routine radiation therapy practice in the Netherlands and associated LLR rates.

METHODS AND MATERIALS

Patients with a primary tumor ≤8 cm of the anorectal junction, cT3-4 stage, and at least 1 internal iliac or obturator LLN with short axis ≥5 mm who received neoadjuvant (chemo)radiation therapy, were selected from a national, cross-sectional study of patients with rectal cancer treated in the Netherlands in 2016. Magnetic resonance images and radiation therapy treatment plans were reviewed regarding segmented LLNs as gross tumor volume (GTV), location of LLNs within clinical target volume (CTV), and received proportion of the planned radiation therapy dose.

RESULTS

A total of 223 out of 3057 patients with at least 1 LLN ≥5 mm were selected. Of those, 180 (80.7%) LLNs were inside the CTV, of which 60 (33.3%) were segmented as GTV. Overall, 202 LLNs (90.6%) received ≥95% of the planned dose. Four-year LLR rates were not significantly higher for LLNs situated outside the CTV compared with those inside (4.0% vs 12.5%, P = .092) or when receiving <95% versus ≥95% of the planned radiation therapy dose (7.1% vs 11.3%, P = .843), respectively. Two of 7 patients who received a dose escalation of 60 Gy developed an LLR (4-year LLR rate of 28.6%).

CONCLUSIONS

This evaluation of routine radiation therapy practice showed that adequate coverage of LLNs was still associated with considerable 4-year LLR rates. Techniques resulting in better local control for patients with involved LLNs need to be explored further.