Response-specific adriamycin sensitivity markers provided by in vivo 31P nuclear magnetic resonance spectroscopy in murine mammary adenocarcinomas.

The in vivo phosphorus-31 nuclear magnetic resonance (NMR) spectra of Adriamycin (ADR)-sensitive murine mammary adenocarcinomas (17/A) and an ADR-resistant subline of this tumor which has been isolated in vivo (17/A/ADR) were compared both before and after i.v. administration of 12 mg/kg ADR. Significant differences between ADR-sensitive and -resistant tumors for the changes observed 1 day after treatment (prior to significant decreases in tumor size) included: the pH increased to greater than 7.3 in response to treatment (or pH remained elevated) in ADR-sensitive tumors only; the inorganic phosphate to nucleoside triphosphates peak height ratio decreased to less than 1 in response to treatment only in ADR-sensitive tumors; glycerophosphocholine to nucleoside triphosphates peak height ratio decreased in response to treatment in ADR-sensitive tumors only; and the phosphocholine to nucleoside triphosphates peak height ratio decreased in response to treatment in ADR-sensitive tumors only. These differences are evidence in support of the hypothesis that in vivo 31P-NMR provides response-specific markers of ADR sensitivity. Because 31P-NMR can be applied to humans, these differences may be of prognostic value in the clinical management of human breast cancer if they are present after treatment with lower, nontoxic doses of ADR.