Recent Trends in Use of Adjuvant Chemotherapy in Elderly Stage II– III Non-Small Cell Lung Cancer

Takefumi Komiya; Emily Powell; Achuta Kumar Guddati

Disclosures

Transl Lung Cancer Res. 2020;9(4):1180-1186. 

In This Article

Discussion

Researchers design and execute trials in various clinical settings. They are expected to address clinically relevant questions to provide guidance for clinicians. However, patient selection for these studies is often skewed by patient selection based on clinical characteristics for safety reasons. Elderly populations are often underrepresented in clinical trials because physician investigators are reluctant to enroll them due to safety concerns. These patients often have poor performance status and/or significant comorbidities that might influence toxicity analyses.

Adjuvant chemotherapy became standard of care in the setting of surgically resected stage II–III and large (T ≥4 cm) stage I based on several phase III trials and meta-analyses.[2–8,18–20] However, only a small number of elderly patients were enrolled in the studies. A retrospective study using SEER data showed that chemotherapy use in the age 66+ population was approximately 30–40% in 2003–2006 despite increasing since 2000.[11] Recent trends in the use of adjuvant chemotherapy have not yet been reported.

Our study demonstrates that increased use of chemotherapy was greater in the age 70–79 group than in other age groups. The increase in the age 70–79 group was also more prominent in patients with stage II disease. Chemotherapy use remained low (approximately 30%) in the age 80+ group.[11] Although the SEER database only provides presence or absence of chemotherapy use, we consider the majority of cases to have received adjuvant chemotherapy based on previous SEER-Medicare analysis data, which indicates that only 3.9% of patients received neoadjuvant chemotherapy.[12] The increase in 5-year overall survival was modest in the age 20–69 and 70–79 groups (Figure 4). There is minimal increase in 5-year overall survival in the age 80+ group.

We, however, acknowledge limitations in this study. As discussed previously, the SEER dataset does not define the timing of chemotherapy in relation to surgery, e.g., neoadjuvant, adjuvant, although it was classified into the "yes" category only if chemotherapy was delivered as first course of treatment. We assume that most patients probably received adjuvant chemotherapy based on previous reports.[12] We did not exclude patients who died within the immediate post-surgical period. No detailed information about chemotherapy (e.g., number of cycles or regimens) was available. The analyses in this study were intended to review populations in the US for which Caucasians dominate. Trends in other ethnic groups or nations are unknown.

The use of the AJCC 6th version of staging system may limit the interpretation. Because SEER adopted the AJCC 7th version in 2010, cases prior to 2010 have never been staged based on the 7th version. We therefore were limited to use of the 6th version due to its consistent availability throughout the study period. Major differences between the 6th and 7th versions in surgical N0 cases were tumors with T >7 cm (T2/stage IB vs. T3/stage IIB, n=457) and T=5–7 cm (T2/stage IB vs. T2b/stage IIA, n=1,016), respectively.[21] These tumors will be classified as stage II or III in the 8th edition requiring adjuvant chemotherapy. These cases staged as stage I according to 6th edition were not included in the current analysis. However, previous adjuvant trials using the 6th version demonstrated chemotherapy benefit in node positive cases. Because all the three versions of AJCC staging systems take N1+ for stage II and higher, most cases that benefit from chemotherapy in the 6th version remain stage II–III.

Nevertheless, we believe this study assists practicing oncologists in determination of whether to use adjuvant chemotherapy in elderly populations. Further research is needed to determine whether adjuvant chemotherapy should be recommended in age 80+ group.

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