[Risk factors for cancer-related cognitive impairment in breast and colorectal cancer patients who undergo chemotherapy]

BACKGROUND

Our study aims to evaluate the impact of different factors on cancer-related cognitive impairment in patients who undergo chemotherapy.

METHODOLOGY

Prospective longitudinal single-centre study that included patients with breast and colon carcinoma who underwent chemotherapy as part of their treatment. Clinical and genetic characteristics of the patients (single nucleotide polymorphisms, SNPs) were collected. Patients' neurocognitive status was assessed using eleven validated tests at three time points: before chemotherapy (M0 - baseline), between one and four weeks after completing chemotherapy (M1), and between 24-30 weeks after completing chemotherapy (M2).

RESULTS

Sixty-two patients were included in this study; 82% were female, median age was 56 years (range 30-74), and 64.5% had been diagnosed with breast cancer. Overall, better cognitive results at M0 were associated with age < 55 years, higher educational level, absence of comorbidities, and the CC variant rs471692 (TOP2A). Significant decline was found between M0 to M1 in the Rey Auditory Verbal Learning Test and the Letter and Number test, with evidence of recovery in M2 compared to M0 regarding the following test: Visual Memory, Functioning Assessment Short Test (FAST), Digit Symbol Substitution and Cube. In the multivariate analysis, being =55 years of age, adjuvant chemotherapy, presence of comorbidities, tobacco and alcohol use, and GT variant rs1800795 were associated with cognitive decline between M0 and M1.

CONCLUSION

Being =55 years of age, female, presence of comorbidities and basic education level are related to a higher risk of cognitive impairment after chemotherapy.

Double heterozygous mutation in the BRCA1 and ATM genes involved in development of primary metachronous tumours: a case report

PURPOSE

Between 5 and 10% of cases of breast cancer (BC) are attributable to a genetic susceptibility. The BRCA1 and BRCA2 genes described in the late 1990s are associated with an increased risk of breast and ovarian cancer, and the clinical management of carriers of pathogenic variants in these genes is defined in several clinical guidelines (Paluch-Shimon et al. in Ann Oncol 27(suppl 5):v103-v110, 2016; Llort et al. in Clin Transl Oncol 17(12):956-961, 2015). However, the pathogenic variants in BRCA1 and BRCA2 represent only a third of the causes of hereditary BC (Easton et al. in N Engl J Med 372:2243-2257, 2015). The incorporation of NGS (Next Generation Sequencing) techniques in the genetic diagnosis of this pathology, in addition to minimising the cost and time of analysis, allows the simultaneous study of other genes of high and moderate penetrance (Easton et al. in N Engl J Med 372:2243-2257, 2015; Op. Cit.; Tung et al. in Cancer 121(1):25-33, 2015). To date, there are not many cases or series of patients that describe the co-occurrence of two pathogenic variants in these genes of BC. Cases of double heterozygosis have been described with the presence of pathogenic variants in BRCA1, BRCA2, PALB2, CHEK2, BLM or NBN (Nomizu et al. in Breast Cancer 22(5):557-61, 2015; Heidemann et al. in Breast Cancer Res Treat 134(3):1229-1239, 2012; Zuradelli et al. in Breast Cancer Res Treat 124(1):251-258, 2010; Sokolenko et al. in Breast Cancer Res Treat 145(2):553-562, 2014).

METHODS

We report the case of a patient diagnosed with multiple tumours who presented two pathogenic variants in heterozygosis.

RESULTS

Two pathogenic variants, c.5123C > A (p.Ala1708Glu) in the BRCA1 gene and c.2413C > T (p.Arg805X) in the ATM gene were detected in heterozygosis. Said variants were confirmed by Sanger-type sequencing using specific primers.

CONCLUSIONS

The implementation of gene panels using NGS in the study of hereditary cancer involves the detection of heterozygous double mutations in genes of high and moderate penetrance for cancer, although with a low frequency.

C-terminal end and aminoacid Lys48 in HMG-CoA lyase are involved in substrate binding and enzyme activity

3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) lyase adopts a (betaalpha)(8) TIM barrel structure with an additional beta9, alpha11 and alpha12 helices. Location of HMG part of the substrate has been suggested but the binding mode for the CoA moiety remains to be resolved. As mutation F305 fs(-2), which involves the last 21 residues of the protein, and mutation K48N caused 3-hydroxy-3-methylglutaric aciduria in two patients, we examined the role of the C-terminal end and Lys(48) in enzyme activity. Expression studies of various C-terminal-end-deleted and K48N-mutated proteins revealed that residues 311-313 (localized in the loop between alpha11 and alpha12 helices) and Lys(48) are essential for enzyme activity. An in silico docking model locating HMG-CoA on the surface of the enzyme implicates Asn(311) and Lys(313) in substrate binding by establishing multiple polar contacts with phosphate and ribose groups of adenosine, and Lys(48) by contacting the carboxyl group of the panthotenic acid moiety.