Elsevier

Lung Cancer

Volume 68, Issue 1, April 2010, Pages 111-114
Lung Cancer

The occurrence of hyponatremia in SCLC and the influence on prognosis: A retrospective study of 453 patients treated in a single institution in a 10-year period

https://doi.org/10.1016/j.lungcan.2009.05.015Get rights and content

Abstract

Hyponatremia is often seen in SCLC, and is thought to be caused by the paraneoplastic syndrome SIADH. Variable results of the prognostic significance of low P-sodium (P-Na) have been reported. This study was performed to investigate the prognostic value of hyponatremia in SCLC. Data was obtained from files from 453 patients diagnosed with SCLC and treated at Odense University Hospital from 1995 to 2005 in which data on P-sodium was available. The standard chemotherapy was six cycles of carboplatin–etoposide. P-Na was <125 mEq/L in 47 patients (11%) and 126–135 mEq/L in 151 (33%), and 255 patients (56%) showed normal values. The median survival was 11.2 months in patients with normal P-Na, and 7.1 months in patients with subnormal values (p = 0.0001). In a Cox multivariate analysis of the 402 patients treated with carboplatin–etoposide, hyponatremia was associated with poorer prognosis. Other independent prognostic factors included LDH, gender, age, performance status, stage, and low value of albumin. Treatment prior to year 2000 was of border line significance, while in-significant factors included hemoglobin level, WBC and alkaline phosphatase. In 61 patients with P-Na <130 mEq/L receiving two or more cycles of chemotherapy, only 15 of the 61 patients (25%) normalized the value of P-Na to 136 mEq/L or above at the time of the second cycle of chemotherapy. The patients who did not fully regain normal values of P-Na, had poorer survival compared with the patients who did in a univariate analysis (p = 0.027), and in a Cox multivariate analysis. In conclusion, hyponatremia was a significant prognostic factor associated with poor prognosis and so was failure to normalize P-Na within the first two cycles of chemotherapy.

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Background

In Denmark, approximately 400–500 people are diagnosed with small-cell lung cancer every year. Hyponatremia is very often seen in SCLC, and is proposed caused by the paraneoplastic syndrome SIADH. The prognostic significance of low plasma sodium (P-Na) has been found in some, but not in the majority of the published studies. This study was performed to investigate the prognostic value of hyponatremia in SCLC

Methods

Data was obtained from the patient files from all 455 patients diagnosed with SCLC and treated with chemotherapy at Odense University Hospital from January 1st 1995 to August 31st 2005. In 453 cases, data on the P-Na values at treatment start was available. A total of 402 patients were treated with carboplatin (AUC5) day 1 and etoposide 120 mg/m2 i.v. or 240 mg/m2 orally day 1–3 every 3–4 weeks to a maximum of six cycles. The remaining patients, except for one, were treated with etoposide as

Results

The basic characteristics of the evaluable patients are shown in Table 1. The median value of P-Na was 136 mEq/L. P-Na was <125 mEq/L in 47 patients (11%), between 126 and 135 mEq/L in 151 (33%), and 255 patients (56%) showed normal values of P-Na. A total of 44% of the patients presented with P-Na below the lower limit of normal (LLN, Fig. 1). Statistical significant lower values of P-Na were found in patients with extensive disease (ED) compared with limited disease (LD), although the difference

Discussion

Hyponatremia is a common phenomenon in SCLC. The value of 135 mEq/L is the LLN of P-Na, and values below that are by many defined as hyponatremia while other reserve this term for values below 130 mEq/L. In our study 44% had subnormal values at presentation, and 16% had hyponatremia defined as a value less than 130 mEq/L, and 10% had severe hyponatremia defined as a value of 125 mEq/L or below. Symptoms of moderate hyponatremia include tiredness, disorientation, headache, muscle cramps, and nausea,

Conflict of interest

None

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