P-31 METABOLISM OF POSTMENOPAUSAL BREAST-CANCER STUDIED IN-VIVO BY MAGNETIC-RESONANCE SPECTROSCOPY

We have studied the metabolism of P-31-containing metabolites of post- menopausal breast cancers in vivo using magnetic resonance spectroscop y (MRS) and a 5.5 cm surface coil. Spectra were acquired from 23 women (four previously treated and 19 previously untreated) with breast can cers more than 3.5 cm in diameter. The spectra of the 19 previously un treated tumours had significantly higher phosphomonoester (PME) P-31 r elative peak areas than the normal breasts of eight post-menopausal wo men (11.7% and 7.7% respectively, P = 0.002). Although an increased PM E relative peak area was characteristic of malignancy, PME relative pe ak area is similarly raised in lactating breast and, therefore, not a specific feature of cancer. An apparently lower nucleotide triphosphat e (NTP) relative peak area in tumours than healthy postmenopausal brea st was secondary to the differences in PME relative peak area; contami nation by signal from chest wall muscle probably accounts for the oste nsibly higher phosphocreatine (PCr) relative peak area of the tumours. Spectroscopy was repeated following chemotherapy in six women. An inc rease in PCr relative peak area was seen in all five patients who resp onded, but again this may represent increased contamination secondary to changes in tumour size. A fall in PME relative peak area was noted in four responders, but also one non-responder, so this finding may ne t be sufficiently specific to be of use clinically. Further studies ar e needed to elucidate fully the role of MRS in breast cancer.