Human milk for cancer care: Science-in-extension and gendered digital labor.

This qualitative case study examines how human milk is framed, negotiated, and justified as a therapeutic resource for adults with cancer within a large digital peer-to-peer human milk-sharing community. Drawing on discourse analysis of posts and comment threads from an online group dedicated to milk donation for oncology patients, the study analyzes how participants construct therapeutic meaning in a context marked by biomedical uncertainty and limited institutional guidance. The findings show that members selectively draw on a pragmatic mode of reasoning we term 'Science-in-Extension', in which biomedical language and principles are selectively appropriated and applied beyond their established evidentiary contexts. Rather than fully rejecting biomedical authority, participants appear to rework it in pragmatic ways within a digitally mediated space of uncertainty. PARTICIPANTS: draw on scientific terminology, experiential testimony, and recontextualized lactation knowledge, alongside culturally resonant understandings of human milk as natural, protective, and morally valued, to render this practice plausible and meaningful. These discourses are embedded in a gendered moral economy that helps organize the circulation of milk through hierarchies of donor purity, milk quality, and recipient suitability. The analysis suggests that digital communities can function as sites where caregiving labor, hope, embodied experience, and biomedical language converge to make this practice appear meaningful and reasonable. The study contributes to medical sociology by illuminating how informal health practices take shape within structural conditions of epistemic ambiguity, and by showing how digital care networks may provide justifications for informal practices that interact in complex ways with formal medicine.