Characteristics of pathologic complete response for locally advanced rectal cancer.

BACKGROUND: Neoadjuvant chemoradiation (NACRT) is the standard of care for locally advanced rectal cancers. The purpose of this study was to determine patient and tumor factors associated with a pathologic complete response (pCR). METHODS: The National Surgical Quality Improvement Program proctectomy-targeted database was utilized to identify all patients from 2016 to 2020 who underwent NACRT followed by proctectomy with curative intent for T3-4N0-2 rectal cancers. RESULTS: A total of 1891 patients were included, of which 253 (13.4%) demonstrated a pCR. Pretreatment N0 staging was associated with a higher rate of pCR (18.9%) when compared to N1 (6.7%) and N2 (6.7%) (p < 0.0001). Patients clinically staged at T3N0 had the highest rate of pCR (19.5%). Gender, age, race, weight, smoking status, and tumor height were not associated with pCR. CONCLUSIONS: Patients with cN0 disease were more likely to experience a pCR compared to cN1-2 patients. Tumor height relative to anal verge or patient demographics were not associated with pCR.

Fungal nutrient allocation in common mycorrhizal networks is regulated by the carbon source strength of individual host plants.

Common mycorrhizal networks (CMNs) of arbuscular mycorrhizal (AM) fungi in the soil simultaneously provide multiple host plants with nutrients, but the mechanisms by which the nutrient transport to individual host plants within one CMN is controlled are unknown. Using radioactive and stable isotopes, we followed the transport of phosphorus (P) and nitrogen (N) in the CMNs of two fungal species to plants that differed in their carbon (C) source strength, and correlated the transport to the expression of mycorrhiza-inducible plant P (MtPt4) and ammonium (1723.m00046) transporters in mycorrhizal roots. AM fungi discriminated between host plants that shared a CMN and preferentially allocated nutrients to high-quality (nonshaded) hosts. However, the fungus also supplied low-quality (shaded) hosts with nutrients and maintained a high colonization rate in these plants. Fungal P transport was correlated to the expression of MtPt4. The expression of the putative ammonium transporter 1723.m00046 was dependent on the fungal nutrient supply and was induced when the CMN had access to N. Biological market theory has emerged as a tool with which the strategic investment of competing partners in trading networks can be studied. Our work demonstrates how fungal partners are able to retain bargaining power, despite being obligately dependent on their hosts.