Association between long-term neuro-toxicities in testicular cancer survivors and polymorphisms in glutathione-s-transferase-P1 and -M1, a retrospective cross sectional study

<p>Abstract</p> <p>Background</p> <p>To assess the impact of polymorphisms in Glutathione S-transferase (GST) -P1, -M1, and -T1 on self-reported chemotherapy-induced long-term toxicities in testicular cancer survivors (TCSs).</p> <p>Methods</p> <p>A total of 238 TCSs, who had received cisplatin-based chemotherapy at median twelve years earlier, had participated in a long-term follow-up survey which assessed the prevalence of self-reported paresthesias in fingers/toes, Raynaud-like phenomena in fingers/toes, tinnitus, and hearing impairment. From all TCSs lymphocyte-derived DNA was analyzed for the functional A→G polymorphism at bp 304 in <it>GSTP1</it>, and deletions in <it>GST-M1 </it>and <it>GST-T1</it>. Evaluation of associations between GST polymorphisms and self-reported toxicities included adjustment for prior treatment.</p> <p>Results</p> <p>All six evaluated toxicities were significantly associated with the cumulative dose of cisplatin and/or bleomycin. Compared to TCSs with either <it>GSTP1-AG </it>or <it>GSTP1</it>-<it>AA</it>, the 37 TCSs with the genotype <it>GSTP1-GG</it>, were significantly less bothered by paresthesias in fingers and toes (p = 0.039, OR 0.46 [0.22–0.96] and p = 0.023, OR 0.42 [0.20–0.88], respectively), and tinnitus (p = 0.008, OR 0.33 [0.14–0.74]). Furthermore, absence of functional GSTM1 protected against hearing impairment (p = 0.025, OR 1.81 [1.08–3.03]).</p> <p>Conclusion</p> <p>In TCSs long-term self-reported chemotherapy-induced toxicities are associated with functional polymorphisms in <it>GSTP1 </it>and <it>GSTM1</it>. Hypothetically, absence of GST-M1 leaves more glutathione as substrate for the co-expressed GST-P1. Also intracellular inactivation of pro-apoptotic mediators represents a possible explanation of our findings. Genotyping of these GSTs might be a welcomed step towards a more individualized treatment of patients with metastatic testicular cancer.</p

Long-Term and Late Effects of Germ Cell Testicular Cancer Treatment and Implications for Follow-Up

Germ cell testicular cancer (TC) represents a malignancy with high cure rates. Since the introduction of cisplatin-based chemotherapy in the late 1970s, the 5-year survival rate has increased considerably, and it is currently above 95%. Because TC is usually diagnosed before the age of 40 years, these men can expect to live for another 40 to 50 years after being successfully treated. This success, however, is hampered by an increased risk of long-term and late effects of treatment. Secondary malignant neoplasms and cardiovascular disease represent the most common potentially life-threatening late effects, typically occurring more than 10 years after treatment. Other long-term effects include pulmonary toxicity, nephrotoxicity, neurotoxicity, decreased fertility, hypogonadism, and psychosocial problems. The incidence and time to onset of these various adverse effects vary according to treatment type and intensity. There is still little knowledge about underlying mechanisms and genetic susceptibility of the various adverse effects. Apart from treatment burden, it is not yet possible to identify patients who are at high risk for certain late effects after TC treatment. In this clinical review, we present the current status regarding different somatic and psychosocial long-term late effects after treatment for TC, based on Medline searches and our own research. Moreover, we postulate recommendations for general medical evaluations that should begin after treatment is completed and continue during follow-up