Scintigraphic prediction of resistance to radiation and chemotherapy in patients with lung carcinoma - Technetium 99m-tetrofosmin and thallium-201 dual single photon emission computed tomography study

BACKGROUND. Various prognostic markers for lung carcinoma have been propose d, but to the authors' knowledge none is noninvasive and convenient for cli nical use. The current study examined the utility of several radiotracers f or the prediction of multidrug resistance (MDR) and radioresistance in pati ents with lung carcinoma. METHODS, Thirty patients with untreated lung carcinoma underwent a dual iso tope single photon emission computed tomography (SPECT) scan at 10 minutes and 120 minutes after the injection of technetium-99m (Tc-99m)-tetrofosmin (Tc-99m-TF) (370 megabecquerels [MBq]) and thallium-201 ((TlCl)-Tl-201) (11 1 MBq). Retention of each tracer was evaluated semiquantitatively. Using ra diation and chemotherapy (cisplatin plus etoposide), the patients either we re treated sequentially (n = 12) or concurrently (n = 18). The relation bet ween therapeutic response and retention of each tracer was analyzed. The de tectability of radioresistance was examined. RESULTS. In patients treated with sequential therapy, the response to radia tion was predicted by 99mTc-TF retention, whereas Tl-201 retention was foun d not to be predictive. Regardless of whether the sequential or concurrent protocol was applied, 14 of 18 tumors with high 99mTc-TF retention (greater than or equal to 15%) exhibited a favorable response to chemoradiotherapy whereas all 12 tumors with low Tc-99m-Tf retention (less than or equal to 1 5%) did not respond to the therapy. In contrast, Tl-201 retention was not f ound to be a predictive factor. CONCLUSIONS. The employed SPECT method is a useful tool for the in vivo pre diction of radioresistance, P-glycoprotein (P-gp), and non-P-gp MDR in lung carcinoma. Low Tc-99m-TF retention serves as a strong predictor of therape utic resistance. High 99mTc-TF retention implies a favorable response. Tl-2 01 did not appear to be a predictive factor but is required for localizatio n of the lesion on SPECT imaging. (C) 1999 American Cancer Society.