998P - Incidence and risk factors of hypomagnesemia in head and neck cancer patients treated with cetuximab

Date 29 September 2014
Event ESMO 2014
Session Poster Display session
Topics Anti-Cancer Agents & Biologic Therapy
Complications of Treatment
Head and Neck Cancers
Presenter Tomohiro Enokida
Citation Annals of Oncology (2014) 25 (suppl_4): iv340-iv356. 10.1093/annonc/mdu340
Authors T. Enokida1, S. Suzuki2, T. Wakasugi3, T. Yamazaki1, M. Tahara1
  • 1Head And Neck Medical Oncology, National Cancer Center Hospital East, 2778577 - Kashiwa/JP
  • 2Pharmacy Dept., National Cancer Center Hospital East, 277 - Kashiwa/JP
  • 3Head And Neck Medical Oncology, National Cancer Center Hospital East, 277-8857 - Kashiwa/JP

Abstract

Aim

Hypomagnesemia is an adverse event during cetuximab treatment. However, the incidence and risk factors of hypomagnesemia in head and neck cancer patients have not been clarified. The aim of this study is to identify clinical features and risk factors of hypomagnesemia caused by cetuximab-containing therapy in head and neck cancer patients.

Methods

We retrospectively reviewed 113 head and neck cancer patients who received cetuximab-containing therapy from February 2012 to March 2014. Main eligibility criteria were ≥3 cetuximab administrations, no prior EGFR-directed therapy, and no prophylactic Mg supplementation.

Results

Median baseline serum Mg level and number of cetuximab administrations were 2.2 mg/dl (range 1.8-2.6) and 8 (range 3-25), respectively. Overall incidence of hypomagnesemia was 46.9% (grade 1, 43.3%; grade 2, 2.6%; grade 3, 0%; grade 4, 0.8%) and differed between patients treated with bioradiation (cetuximab and radiation) and palliative chemotherapy (26% vs. 58%; p < 0.01). Independent risk factors were low baseline serum Mg (OR 0.01, 95% CI 0.00-0.29), ≥7 cetuximab administrations (OR 4.02, 95% CI 1.16-13.98), and concurrent administration of platinum (cisplatin or carboplatin; OR 5.44, 95% CI 1.77-16.7). Respective incidence of hypomagnesemia in patients in high- (concurrent platinum and ≥7 cetuximab administrations) and low-risk (no concurrent platinum and <7 cetuximab administrations) groups was 66.0% and 6.6% (p < 0.001, OR 27.2, Table 1). Of all planned cetuximab administrations, treatment was ceased due to hypomagnesemia in 0.4% (n = 1074).

Conclusions

While prophylactic Mg supplementation is not absolutely necessary, special attention should be given to high-risk patients, namely those with low baseline Mg level, high number of cetuximab administrations, and concurrent platinum.

Hypomagnesemia in high- and low- risk groups
High-risk group Low-risk group
(n = 53) (n = 15) p-value OR
Median baseline Mg [mg/dl] (range) 2.2 (1.8, 2.6) 2.3 (1.9, 2.6) p = 0.23 -
Median Δ Mg* [mg/dl] (range) -0.5 (0, -1.2) -0.3 (0, -0.8) p < 0.01 -
Median Δ Mg %** [%] (range) -25 (0, -67) -13 (0, -31) p < 0.001 -
Hypomagnesemia*** 66.0% 6.6% p < 0.001 27.2

*Minimum Mg - Baseline Mg, **Δ Mg / Baseline Mg, ***All grades Mann-Whitney U test, Fisher's exact test.

Disclosure

All authors have declared no conflicts of interest.