Prognostic Significance of Procalcitonin in Small Cell Lung Cancer

Kosuke Ichikawa; Satoshi Watanabe; Satoru Miura; Aya Ohtsubo; Satoshi Shoji; Koichiro Nozaki; Tomohiro Tanaka; Yu Saida; Rie Kondo; Satoshi Hokari; Nobumasa Aoki; Yasuyoshi Ohshima; Toshiyuki Koya; Toshiaki Kikuchi

Disclosures

Transl Lung Cancer Res. 2022;11(1):43-52.

Abstract and Introduction

Abstract

Background: Procalcitonin (PCT) is a serological marker whose utility has been established in infectious disease areas. Although serum calcitonin is a prognostic predictor in patients with medullary thyroid carcinoma, the clinical usefulness of PCT remains unclear in lung cancer patients.

Methods: As a discovery cohort, we retrospectively analyzed consecutive patients with non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) who received first-line chemotherapy at our institution, and PCT blood levels were measured. As the validation cohort, PCT blood levels were prospectively evaluated in SCLC patients before first-line chemotherapy. The correlation between a PCT increase and prognosis was examined in the discovery and validation cohorts.

Results: Twenty-three SCLC patients and 26 NSCLC patients were enrolled as the discovery cohort, and 30 SCLC patients were enrolled as the validation cohort. The PCT level in SCLC patients was significantly higher than that in NSCLC patients. The PCT level was not associated with WBC count and weakly associated with the CRP level. In both the discovery and validation cohorts, the median survival time was significantly shorter in SCLC patients with PCT-high than in SCLC patients with PCT-normal (discovery; 11.7 vs. 89.7 months, P<0.005, validation; 9.6 vs. 22.6 months, P<0.005).

Conclusions: It may be difficult to differentiate bacterial infections in SCLC patients by PCT, as PCT is elevated even in SCLC patients without infectious diseases. This is the first study to prospectively verify that pretreatment PCT levels have a significant negative correlation with prognosis in SCLC patients.

Introduction

Small cell lung cancer (SCLC) is one of the primary lung cancers of neuroendocrine origin and is strongly associated with smoking and characterized by rapid progression. SCLC is classified into limited disease (LD) and extensive disease (ED) depending on the degree of progression. Because of the sensitivity of SCLC to chemotherapy and radiation therapy, one of the standard initial treatments of SCLC is platinum-based chemotherapy with or without radiotherapy, which is known to cause febrile neutropenia in 10–20% of patients.^[1]

Procalcitonin (PCT) is a 13-kDa peptide consisting of 116 amino acids^[2] that is usually synthesized in thyroid C cells as a precursor of calcitonin.^[3] PCT has a stable half-life of 24 to 30 hours and very low serum levels. In recent years, PCT has attracted attention as an indicator of the severity of bacterial and fungal infections.^[4] In addition, compared to conventional inflammatory markers such as C-reactive protein (CRP) and leukocyte count, PCT has superior sensitivity and specificity in bacterial and fungal infections and is used to distinguish it from viral infections and noninfectious diseases.^[5] As its clinical usefulness has become known, a precise and simple test method for PCT has been established. The secretion of calcitonin from medullary thyroid carcinoma, SCLC, and neuroendocrine tumors has been reported.^[6,7] Specifically, in medullary thyroid carcinoma, an increase in serum calcitonin is known as a prognostic predictor.^[5] Neuroendocrine cells in the lung were suggested as the origin of SCLC.^[8] Calcitonin related polypeptide alpha encodes calcitonin and calcitonin gene-related peptide (CGPR). Because neuroendocrine cells widely express calcitonin gene related protein, tumorigenesis of these cells may result in elevation of production of PCT and calcitonin. The usefulness of calcitonin as a tumor marker or prognostic factor has been investigated in SCLC, but no conclusion has been reached.^[9] Similarly, PCT is also expected to be secreted from SCLC and might be a prognostic predictor in SCLC patients. Indeed, Patout et al. reported that the increase of serum PCT and the negative correlation between serum PCT level and prognosis in patients with lung cancer with neuroendocrine component.^[10] However, few reports so far have evaluated the increase in serum levels in patients with SCLC.^[11,12] As mentioned earlier, SCLC is usually treated with intense radiotherapy and chemotherapy, and fever often occurs during the course of treatment, but it is not known whether PCT is useful to distinguish between infectious and noninfectious fever when SCLC patients develop fever.

The purpose of this study was to evaluate serum PCT levels in patients with SCLC and to investigate the value of PCT as a prognostic factor. We present the following article in accordance with the STROBE reporting checklist (available at https://tlcr.amegroups.com/article/view/10.21037/tlcr-21-838/rc).

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Abstract and Introduction
Methods
Results
Discussion
References

Table 1. Baseline characteristics of the patients
Main characteristics	Discovery cohort, N=23	Validation cohort, N=30	P
Median age [range], y	62 [47–72]	67 [50–85]	0.005
Sex			0.118
Male	23 (100%)	27 (90%)
Female	0 (0%)	3 (10%)
Stage			0.206
LD	10 (43%)	13 (43%)
ED	13 (57%)	17 (57%)
ECOG performance status		0.177
0	7 (30%)	6 (20%)
1	9 (39%)	14 (47%)
2	2 (9%)	5 (17%)
3	2 (9%)	3 (10%)
4	0 (0%)	2 (7%)
NA	3 (13%)	0 (0%)
1st line chemotherapy		0.068
CDDP + ETP	10 (43%)	11 (37%)
CDDP + CPT–11	1 (4%)	5 (17%)
CBDCA + ETP	8 (35%)	12 (40%)
Ifosphamide + CBDCA + ETP	4 (18%)	0 (0%)
CDDP + PTX + AMR + NGT	0 (0%)	2 (7%)
Radiotherapy			0.754
+	6 (26%)	9 (30%)
−	17 (74%)	21 (70%)
Surgery			0.440
+	1 (4%)	3 (10%)
−	22 (96%)	27 (90%)

Table 2. Patient characteristics according to procalcitonin level
Characteristics	Discovery cohort			Validation cohort
Characteristics	PCT normal, N=10	PCT high, N=13	P	PCT normal, N=15	PCT high, N=15	P
Median age [range], y	65 [47–72]	62 [55–71]	0.975	65 [50–81]	73 [62–85]	0.002
Stage
LD/ED	9/1	5/8	0.008	8/7	5/10	0.267
Number of metastatic organ
0/1	10	10	0.052	12	12	0.623
≥2	0	3		3	3
ECOG performance status
0/1	5/3	2/6	0.358	3/9	3/5	0.117
2/3/4	1/0/1	1/2/2		3/0/0	2/3/2
Response
CR/PR	7/2	2/6	0.304	4/10	0/10	0.690
SD/PD/NA	0/1/0	3/0/2		1/0/0	1/2/2
Tumor markers
NSE normal/high/NA	10/0	5/8	<0.005	6/9/0	7/7/1	0.588
ProGRP normal/high	3/7	0/13	0.059	6/9	0/15	<0.005

Table 3. Univariate and multivariate Cox proportional hazard model results for OS
Characteristic	OS
	Univariate			Multivariate
	HR	95% CI	P	HR	95% CI	P
Discovery cohort
Stage (ED vs. LD)	6.9	2.143–24.093	0.001	40.6	2.259–964.427	0.012
PCT (high vs. normal)	5.9	1.992–22.051	0.001	19.9	2.594–407.133	0.010
Sex (male vs. female)	–	–	–	–	–	–
Age (≥70 vs. <70)	3.9	0.840–14.415	0.078	2074.8	14.332–1431729	0.005
PS (2/3/4 vs. 0/1)	2.9	0.745–9.718	0.117	3.0	0.402–24.525	0.272
ProGRP (high vs. normal)	3.1	0.858–19.473	0.090	7.8	0.748–266.76	0.133
NSE (high vs. normal)	3.8	1.304–11.716	0.015	0.2	0.039–1.498	0.125
LDH (high vs. normal)	3.3	1.213–9.453	0.020	1.0	0.151–6.219	0.993
Na (low vs. normal)	2.6	0.949–7.245	0.062	6.2	0.867–50.982	0.063
Validation cohort
Stage (ED vs. LD)	6.6	2.527–20.711	<0.001	18.0	2.709–156.014	0.003
PCT (high vs. normal)	2.8	1.165–7.048	0.022	51.3	7.0776–651.06	<0.001
Sex (male vs. female)	0.5	0.165–2.146	0.308	0.1	0.002–2.595	0.147
Age (≥70 vs. <70)	1.4	0.557–3.178	0.488	0.5	0.12–1.928	0.286
PS (2/3/4 vs. 0/1)	2.0	0.795–4.817	0.133	1.9	0.467–7.717	0.372
ProGRP (high vs. normal)	2.1	0.707–9.039	0.197	0.0	0.002–0.45	0.009
NSE (high vs. normal)	3.6	1.438–10.176	0.006	3.7	0.64–21.4	0.140
LDH (high vs. normal)	1.4	0.599–3.322	0.414	0.9	0.204–3.539	0.876
Na (low vs. normal)	2.3	0.974–5.405	0.057	1.4	0.262–7.046	0.699

OS, overall survival; LD, limited disease; ED, extensive disease; PCT, procalcitonin; PS, performance status, NSE, neuron-specific enolase; ProGRP, pro-gastrin-releasing peptide; LDH, lactate dehydrogenase; HR, hazard ratio; CI, confidence interval.

Authors and Disclosures

Kosuke Ichikawa¹, Satoshi Watanabe¹, Satoru Miura², Aya Ohtsubo¹, Satoshi Shoji¹, Koichiro Nozaki¹, Tomohiro Tanaka¹, Yu Saida¹, Rie Kondo¹, Satoshi Hokari¹, Nobumasa Aoki¹, Yasuyoshi Ohshima¹, Toshiyuki Koya¹ and Toshiaki Kikuchi¹

¹Department of Respiratory Medicine and Infectious Diseases, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan; ²Niigata Cancer Center Hospital, Niigata, Japan

Correspondence to
Dr. Satoshi Watanabe. Department of Respiratory Medicine and Infectious Diseases, Niigata University Graduate School of Medical and Dental Sciences, 1–757 Asahimachidori, Chuouku, Niigata, 951–8510, Japan. Email: satoshi7@med.niigata-u.ac.jp.

Contributions
(I) Conception and design: K Ichikawa, S Watanabe; (II) Administrative support: S Watanabe; (III) Provision of study materials or patients: All authors; (IV) Collection and assembly of data: K Ichikawa; (V) Data analysis and interpretation: K Ichikawa; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.

Conflicts of Interest
All authors have completed the ICMJE uniform disclosure form (available at https://tlcr.amegroups.com/article/view/10.21037/tlcr-21-838/coif). KI received lecture fees from AstraZeneca, Chugai Pharma, Bristol-Myers, Boehringer Ingelheim, Ono Pharmaceutical, Taiho Pharmaceutical Novartis International AG and Daiichi Sankyo Company; SW received lecture fees from AstraZeneca, Chugai Pharma, Ono Pharmaceutical, Bristol-Myers, Boehringer Ingelheim, Eli Lilly, MSD, Taiho Pharmaceutical, Pfizer, Novartis and Daiichi Sankyo; SM received lecture fees from Chugai Pharmaceutical, Taiho Pharmaceutical, Pfizer, Eli Lilly, Boehringer-Ingelheim Japan, Ono Pharmaceutical, AstraZeneca, Novartis, MSD, Bristol-Myers Squibb, Kyowa Hakko Kirin and Abbive; SS received lecture fees from AstraZeneca, Chugai Pharma, Taiho Pharmaceutical and MSD; KN received lecture fees from AstraZeneca, Boehringer Ingelheim, Taiho Pharmaceutical and MSD; SH received lecture fees from GlaxoSmithKline inc; NA received lecture fees from MSD and Meiji Seika Pharma; YO received lecture fees from Boehringer-Ingelheim Japan and Meiji seika pharma; T Koya received lecture fees from AstraZeneca, Boehringer-Ingelheim, Sanofi Genzyme, Novartis, Daiichi Sankyo, Kyorin Pharmaceutical and GlaxoSmithKline; T Kikuchi received lecture fees from Chugai Pharma, Boehringer Ingelheim, Eli Lilly, MSD K.K., Astellas Pharma Inc., Taiho Pharmaceutical Co., Ltd., Bristol-Myers Squibb Company, Pfizer Japan Inc., Daiichi Sankyo Co., Ltd., Taisho Toyama Pharmaceutical Co., Ltd., Janssen Pharmaceutical K.K., Japan BCG Laboratory, Ono Pharmaceutical Co., Ltd., Novartis Pharma K.K., Mylan N.V., AstraZeneca, Roche Diagnostics K.K., Shionogi & Co., Ltd., TEIJIN PHARMA Ltd. and KYORIN Pharmaceutical Co., Ltd. The other authors have no conflicts of interest to declare.