CB1 Signalling, Endocrine Allostasis, and Estrogen-Dependent Cancers A Systems-Level Analysis of Tumour Permissivity

Estrogen-dependent cancers are governed not only by tumour genetics, but by long-term endocrine, metabolic, immune, and tissue-level regulation. These diseases are highly sensitive to sustained changes in hormonal signalling context, adaptive capacity, and system-level coordination. As a result, interventions that alter regulatory systems can influence tumour behaviour even when they do not act directly on cancer cells. This paper presents a systems-level analysis of CB1-dominant signalling and endocrine allostasis in estrogen-dependent cancers. Rather than focusing on isolated receptor interactions or short-term cellular effects, it examines how sustained CB1 activation reshapes endocrine feedback precision, estrogen synthesis and receptor balance, metabolic–hormonal coupling, immune surveillance, and stromal signalling over time. These interacting shifts are shown to converge toward tumour-permissive environments in hormonally active tissues. A central contribution of this work is its clarification of why receptor-centric interpretations and in vitro cytotoxicity findings provide false reassurance when extrapolated to living systems. Acute antiproliferative effects observed under controlled laboratory conditions may coexist with longer-term regulatory drift that increases vulnerability through loss of adaptive precision. In estrogen-dependent malignancies, system-level context consistently outweighs isolated molecular mechanisms in determining disease trajectory. Positioned as Paper III within the Context-Dependent Cannabinoid Risk series, this work integrates prior analyses of metabolic and autonomic allostasis with endocrine and oncological consequences. It does not propose changes to clinical guidelines, nor does it argue for or against cannabinoid use in general. Instead, it clarifies risk reasoning relevant to endocrine-active exposures and highlights the importance of indication awareness, selectivity, timing, and long-term system stability in cannabinoid-related clinical decision-making. By framing CB1 signalling as a regulatory modifier rather than a direct oncologic agent, this paper contributes to a more coherent, ethically grounded understanding of cannabinoid biology in hormone-sensitive disease.