Gastrointestinal Cancer

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SU_1_2007 - Prognostic implications of altering the nodal staging for anal cancer in the American Joint Committee on Cancer 8th (AJCC8) Edition Staging Manual

Sunday, October 21
1:15 PM - 2:45 PM
Location: Innovation Hub, Exhibit Hall 3

Prognostic implications of altering the nodal staging for anal cancer in the American Joint Committee on Cancer 8th (AJCC8) Edition Staging Manual
J. K. Elson1, L. A. Kachnic2, J. M. Longo3, R. Tao4, S. R. Amarnath5, S. A. Lloyd6, and J. R. Kharofa Jr7; 1University of Cincinnati, Cincinnati, OH, 2Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, TN, 3Medical College of Wisconsin, Milwaukee, WI, 4University of Utah Huntsman Cancer Institute, Salt Lake City, UT, 5Cleveland Clinic Taussig Comprehensve Cancer Center, Cleveland, OH, 6University of California San Francisco, Department of Radiation Oncology, San Francisco, CA, 7University of Cincinnati Department of Radiation Oncology, Cincinnati, OH

Purpose/Objective(s): The AJCC8 has altered nodal staging for squamous cell carcinoma of the anus (SCCA). Nodal stage is now binary (N0 or N+) in contrast to AJCC7’s three-tiered grouping based on nodal site (N1-N3). AJCC8 has also split AJCC7 overall stage II disease into IIA/IIB and stage III into IIIA/IIIB/IIIC. In this study, we use the National Cancer Database (NCDB) data to evaluate the effect of AJCC8 nodal stage by T stage on 5-year overall survival (OS). We hypothesize that 5-year OS for each T stage will be similar for patients with former AJCC7 N1-3 groups. The survival differences for the new AJCC8 overall stage grouping and subsets of the new AJCC8 IIIA and IIIC stage groups is also evaluated.

Materials/Methods: The NCDB was used to identify patients with SCCA from 2004-2013. Inclusion criteria were: age ≥ 18; SCCA; Stage (AJCC7) I-III; no surgery; Patients treated with radiation (RT) and chemotherapy; all patients treated definitively without palliation; all RT performed at same institution; total RT dose 36-59.4 Gy; RT to pelvis, nodes, and soft tissue only; RT fractions 25-40; RT time from 25-180 days; and IMRT or 3D only. RT total dose included target volume plus any boost. Each T stage within the AJCC7 was compared with increasing nodal stage. The new AJCC8 stage groups and subsets were compared using log rank tests.

Results: There were 6751 patients who met the inclusion criteria. The 5-year OS by AJCC8 stage was I=81%, IIA=78%, IIB=64%, IIIA=69%, IIIB=59%, IIIC= 57%. For node negative patients, the 5-year OS was T1N0=81%, T2N0=78%, T3N0=65%, and T4N0=59%. In the new AJCC8 IIIA group, there was no difference in 5-year OS for T1N+ or T2N+ patients (70.3% vs 68.6%, p=0.09). However, a difference in 5-year OS was observed for AJCC7 T1 N1-3 (p = 0.0047) and AJCC7 T2 N1-3 patients (p = 0.0389). Table 1 demonstrates the 5-year OS differences between AJCC7 and AJCC8 for early T stages with increasing N stage. In the AJCC8 IIIC group, there was no difference in 5-year OS for T3N+ or T4N+ patients (58% vs 55%, p=0.81). With increasing AJCC7 nodal stage, there was no OS difference for T3 (AJCC7 T3N1=54%, T3N2=64%, T3N3=55% p=0.19) or T4 (AJCC7 T4N1=61%, T4N2=41%, T4N3=59% p=0.35) disease.

Conclusion: This analysis demonstrates that the AJCC7 nodal staging retains prognostic significance for early T stages. For AJCC8 T1/T2 tumors with lymph node involvement, OS is inferior among patients with more advanced nodal stage (AJCC7 N1-3). This difference is not apparent with AJCC8 T3/T4 tumors. The survival in the stage IIIA AJCC8 group is heterogeneous and is largely driven by the burden of nodal disease in patients with T1/T2 cancers.
Table 1
AJCC 8th Stage 5-year OS (%) AJCC 7th Stage 5-year OS (%) p-value
T1N+ 68.6 T1N1 82.9
T1N2 69.4 0.0047
T1N3 46.1
T2N+ 69.0 T2N1 76.0
T2N2 65.6 0.0389
T2N3 63.6

Author Disclosure: J.K. Elson: None. L.A. Kachnic: Research Grant; NCI NCORP, SWOG. Honoraria; Up-to-Date. Trustee; ABR. R. Tao: None. S.R. Amarnath: None. J.R. Kharofa: None.

Joshua Elson, MD, MPH

Biography:
Joshua Elson is a Cincinnati native who went to the University of Michigan for undergraduate and graduate studies. For his Bacchelors of Arts (BA), he majored in the History of Art and Biology. He then completed a Masters in Public Health (MPH) in Epidemiology and International Health. After completion of the MPH, he worked for a year as a clinical research coordinator at the University of California, San Francisco, in the Department of Orthopaedic Surgery. From there he attended Ben-Gurion University of the Negev in Israel for his Doctor of Medicine (MD) degree. He completed his internship in internal medicine at Maimonides Medical Center in Brooklyn, New York. He is completing his residency in Radiation Oncology at the University of Cincinnati.

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