Lynch syndrome (LS) is the main hereditary colorectal cancer syndrome. There have been few reports regarding the clinical and molecular characteristics of LS patients in Latin America; this is particularly true in the Mexican population, where no information is available. The present study aims to describe the clinical and molecular spectrum of variants in a cohort of patients diagnosed with LS in Mexico. We present a retrospective analysis of 412 patients with suspected LS, whose main site of cancer diagnosis was the colon (58.25%), followed by the endometrium (18.93%). Next-generation sequencing analysis, with an extensive multigene panel, showed that 27.1% (112/414) had a variant in one of the genes of the mismatch repair pathway (MMR); 30.4% (126/414) had a variant in non-MMR genes such as CHEK2, APC, MUTYH, BRCA1, and BRCA2; and 42.5% (176/414) had no genetic variants. Most of the variants were found in MLH1. Pathogenic variants (PVs) in MMR genes were identified in 65.7% (96/146) of the total PVs, and 34.24% (45/146) were in non-MMR genes. Molecular and clinical characterization of patients with LS in specific populations allowed personalized follow-up, with the option for targeted treatment with immune checkpoint inhibitors and the development of public health policies. Moreover, such characterization allows for family cascade testing and consequent prevention strategies.

Objective. Describe the prevalence of breast cancer (BC)- associated germline pathogenic variants (PVs) among Mexican patients with triple-negative BC (TNBC). Materials and methods. The spectrum of PVs identified among patients with TNBC who were enrolled in a prospective registry and underwent genetic testing was analyzed. Results. Of 387 patients with invasive TNBC and a median age at diagnosis of 39 years (range 21-72), 113 (29%) were carriers of PVs in BC-susceptibility genes: BRCA1 (79%), BRCA2 (15%), and other (6%: ATM, BRIP1, PALB2, PTEN, RAD51C, and TP53). PV carriers were younger at BC diagnosis (37 vs. 40 years, p=0.004) than non-carriers. Conclusion. A large proportion of TNBC in Mexican patients is associated with germline PVs, the vast majority in BRCA. The incremental yield of PVs in other BC-susceptibility genes was modest, and a stepwise approach starting with BRCA testing may be justified if it is more cost-effective than multigene panel testing.

Cutaneous manifestations can serve as early and sometimes the first clinical indicators in various hereditary cancer predisposition syndromes. This review provides a comprehensive overview of the dermatological signs associated with these syndromes, aiming to facilitate their recognition in clinical practice. Hereditary Breast and Ovarian Cancer syndrome is notably linked to an increased risk of melanoma. BAP1 tumor predisposition syndrome is characterized by BAP1-inactivated melanocytic tumors. Muir–Torre syndrome, a variant of Lynch syndrome, presents with distinctive cutaneous neoplasms such as sebaceous carcinomas, sebaceous adenomas, and keratoacanthomas. PTEN hamartoma tumor syndrome commonly features hamartomatous growths, trichilemmomas, acral keratoses, oral papillomas, and genital lentiginosis. Gorlin syndrome is marked by basal cell carcinomas and palmoplantar pits, while Peutz–Jeghers syndrome is identified by mucocutaneous pigmentation. In familial adenomatous polyposis, the cutaneous findings include epidermoid cysts, fibromas, desmoid tumors, and lipomas. Additionally, we examined monogenic disorders associated with cancer risk and skin involvement, such as xeroderma pigmentosum, neurofibromatosis type 1, familial atypical multiple-mole melanoma syndrome, and Fanconi anemia. The early recognition of these dermatologic features is essential for a timely diagnosis and the implementation of appropriate surveillance strategies in individuals with hereditary cancer syndromes.

The PMS2 gene is involved in DNA repair by the mismatch repair pathway. Deficiencies in this mechanism have been associated with Lynch Syndrome (LS), which is characterized by a high risk for colorectal, endometrial, ovarian, breast, and other cancers. Germinal pathogenic variants of PMS2 are associated with up to 5% of all cases of LS. The prevalence is overestimated for the existence of multiple homologous pseudogenes. We report the case of a 44-year-old woman diagnosed with breast cancer at 34 years without a relevant cancer family history. The presence of pathogenic variant NM_000535.7:c.1A > T, (p.Met1Leu) in PMS2 was determined by next-generation sequencing analysis with a panel of 322 cancer-associated genes and confirmed by capillary sequencing in the patient. The variant was determined in six family members (brothers, sisters, and a son) and seven non-cancerous unrelated individuals. Analysis of the amplified region showed high homology of PMS2 with five of its pseudogenes. We determined that the variant is associated with the PMS2P1 pseudogene following sequence alignment analysis. We propose considering the variant c.1A > T, (p.Met1Leu) in PMS2 for reclassification as not hereditary cancer-related, given the impact on the diagnosis and treatment of cancer patients and families carrying this variant.

BRCA1 and BRCA2 germline pathogenic variants are a matter of concern because of their relevance in cancer risk assessment, personalized treatment options, and cancer prevention. Therefore, the study of quality of life (QoL), although complex, has been a challenge for clinical care and research implications for patients and families with hereditary breast and ovarian cancer (HBOC). This chapter aims to show the evolution of the evaluation of the QoL study according to the current needs of patients with BRCA1/BRCA2 mutations.

Ovarian cancer (OC) is often diagnosed at advanced stages, and resistance to platinum-based chemotherapy remains one of the leading causes of treatment failure. This resistance is sustained in part by metabolic plasticity, particularly through the de novo serine synthesis pathway (SSP), orchestrated by D-3-phosphoglycerate dehydrogenase (PHGDH), which diverts glycolytic carbon toward serine, glycine, and one-carbon (1C) units that fuel nucleotide biosynthesis, epigenetic regulation, and redox homeostasis. Elevated PHGDH expression in OC is associated with advanced International Federation of Gynecology and Obstetrics (FIGO) stage and poorer overall survival; conversely, a subset of tumors downregulates PHGDH at relapse and shifts toward NAD⁺-dependent pathways that sustain poly(ADP-ribose) polymerase (PARP) activity and DNA repair, creating a distinct therapeutic vulnerability. Rather than a contradiction, this bidirectional behavior reflects the metabolic plasticity through which OC adapts to treatment pressure. Therefore, this review analyzes the context-dependent role of PHGDH in OC, the mechanistic basis of divergent associations with therapy resistance, and the current status of pharmacological inhibitors. Preclinical evidence indicates that PHGDH inhibition with CBR-5884 increases oxidative stress, reduces stemness, and restores platinum sensitivity in PHGDH-high models. We further identify the relationship between PHGDH and radiotherapy response as an unexplored question in OC, despite evidence of SSP-dependent radioresistance in other tumor types. Together, these observations position PHGDH as an actionable, but biomarker-dependent, metabolic target in OC.