Thu-Lan T. Luonga; Chelsea N. Powers, PhDa; Brian J. Reinhardt, MSa; Michael J. McAnulty, PhDa; Peter J. Weina, MDb; Karen J. Shou, DOa; Caban B. Ambar, MSa
Correspondence: Thu-Lan T. Luong (thu-lan.t.luong.civ@health.mil)
aWalter Reed National Military Medical Center, Bethesda, Maryland
bFort Belvoir Community Hospital, Virginia
Author disclosures
The authors report no actual or potential conflicts of interest or outside sources of funding with regard to this article.
Disclaimer
The opinions expressed herein are those of the authors and do not necessarily reflect those of Federal Practitioner, Frontline Medical Communications Inc., the Department of Defense, the US Government, or any of its agencies. This article may discuss unlabeled or investigational use of certain drugs. Please review the complete prescribing information for specific drugs or drug combinations—including indications, contraindications, warnings, and adverse effects—before administering pharmacologic therapy to patients.
Ethics and consent
The study protocol was approved by the Walter Reed National Military Medical Center Institutional Review Board and complied with the Health Insurance Portability and Accountability Act as an exempt protocol.
The Joint Pathology Center provided 387 entries for 382 patients aged 21 to 93 years (mean, 65 years) who were treated systemically with erlotinib from January 1, 2001, to December 31, 2020. Five patients had duplicate entries because they had different cancer sites. There were 287 patients (74%) with lung cancer, 61 (16%) with pancreatic cancer, and 39 (10%) with other cancers. For lung cancer, there were 118 patients (30%) for the upper lobe, 78 (20%) for the lower lobe, and 60 (16%) not otherwise specified (NOS). Other lung cancer sites had fewer patients: 21 (5%) middle lobe lung, 6 (2%) overlapping lung lesion(s), and 4 (1%) main bronchus of the lung. For pancreatic cancer, there were 27 patients (7%) for the head of the pancreas, 10 (3%) pancreas NOS, 9 (2%) body of the pancreas, 9 (2%) tail of the pancreas, 4 (1%) overlapping lesions of the pancreas, 1 (< 1%) pancreatic duct, and 1 (< 1%) other specified parts of the pancreas
. Thirty-nine patients (10%) received erlotinib for indications that were not for FDA-approved indications, which included 9 (2%) for kidney NOS, 8 (2%) for the unknown primary site, 5 (1%) for liver cancer, 2 (1%) for intrahepatic bile duct, 2 (1%) for tonsil, and 1 (< 1%) for 13 disease sites (Table 1).
There were 342 patients (88%) who were aged > 50 years; 186 male patients (48%) and 201 female patients (52%). There were 293 patients (76%) who had a cancer diagnosis of stage III or IV disease and 94 (24%) who had a cancer diagnosis of stage ≤ II (combination of data for stage 0, 1, and 2, not applicable, and unknown). For their systemic treatment, 161 patients (42%) were treated with erlotinib alone and 226 (58%) received erlotinib concomitantly with additional chemotherapy.
Of these patients, 287 (74%) were diagnosed with lung cancer (Table 2).
Patients were more likely to discontinue erlotinib for chemotherapy if they received concomitant treatment. Among the patients receiving erlotinib monotherapy, 5% stopped the treatment, whereas 51% of patients treated concomitantly discontinued (P < .001).
The comparisons for lung cancer vs other cancer and those aged ≤ 50 years vs > 50 years were significant (P = .005 and .05, respectively) while other comparisons were not significant (Table 3).
Among the 123 patients who discontinued their treatment, 101 switched treatment with no AEs notes, 22 died or experienced fatigue with blurry vision, constipation, nonspecific gastrointestinal effects, grade-4 diarrhea (as defined by the Common Terminology Criteria for Adverse Events), or developed a pleural fluid, pneumonitis, renal failure, skin swelling and facial rash, and unknown AEs of discontinuation. Patients who discontinued treatment because of unknown AEs had physicians’ notes that detailed emergency department visits, peripheral vascular disease, progressive disease, and treatment cessation, but did not specify the exact symptom(s) that led to discontinuation. The causes of death are unknown because they were not detailed in the available notes or databases. The overall results in this retrospective review cannot establish causality between taking erlotinib or gefitinib and death.
