Journal of Cancer Research and Therapeutics

LETTER TO THE EDITOR
Year
: 2013  |  Volume : 9  |  Issue : 4  |  Page : 754--755

Discordance in 68Ga-DOTANOC and 177Lu-DOTATATE uptake in diagnostic and post-therapy scans in patients with medullary thyroid cancer-likely reasons


Nishikant Avinash Damle, Chandrasekhar Bal, Santosh Gupta, Abhinav Singhal 
 Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India

Correspondence Address:
Nishikant Avinash Damle
Room No. 59 A, Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi - 110 029
India




How to cite this article:
Damle NA, Bal C, Gupta S, Singhal A. Discordance in 68Ga-DOTANOC and 177Lu-DOTATATE uptake in diagnostic and post-therapy scans in patients with medullary thyroid cancer-likely reasons.J Can Res Ther 2013;9:754-755


How to cite this URL:
Damle NA, Bal C, Gupta S, Singhal A. Discordance in 68Ga-DOTANOC and 177Lu-DOTATATE uptake in diagnostic and post-therapy scans in patients with medullary thyroid cancer-likely reasons. J Can Res Ther [serial online] 2013 [cited 2020 Sep 22 ];9:754-755
Available from: http://www.cancerjournal.net/text.asp?2013/9/4/754/126489


Full Text

Sir,

We qualitatively studied the discordance between pre-therapy 68Ga-DOTANOC scans and post-therapy 177Lu-DOTATATE scans in patients with medullary thyroid cancer (MTC). Patients with metastatic/recurrent, inoperable MTC showing good uptake of 68 Ga-DOTANOC on positron emission tomography (PET)/computed tomography (CT); >18 years of age with serum creatinine ≤1.3 mg%, bilirubin ≤1 mg%, SGOT, SGPT ≤50 IU; baseline normalized GFR (2 sample method- 99m Tc-DTPA) ≥70 ml/min/1.73 mr 2 , Hb ≥9 gms%, TLC ≥4000/μl, platelets ≥1,50,000/μl were included in this study.

Fifteen MTC patients (13 male, 2 female; age range: 22-74 years) with a positive 68Ga-DOTANOC PET-CT scan were recruited for 177Lu-DOTATATE therapy. Patient characteristics are detailed in [Table 1] and [Table 2]. Total of 150 mCi of 177Lu-DOTATATE was administered as first therapeutic dose to each patient. Cumulative dose of 600-800 mCi of 177Lu-DOTATATE was infused to each post-therapy scan positive patients who showed good uptake on planar images, over 5-6 cycles (10-12 weeks of interval between each cycle). Eight of 15 (53.3%) patients showed no or poor uptake (defined as no or faint tracer uptake seen on planar images) of 177Lu-DOTATATE and were not given further radionuclide therapy, while 7 patients (46.7%) showed good uptake of 177Lu-DOTATATE and were scheduled for further therapy. Mean serum calcitonin was 7136 pg/ml (median, 3257 pg/ml, range: 245-29406 pg/ml). Mean percentage reduction in serum calcitonin of seven DOTATATE positive patients was 36.93 at 3 months post-therapy. Of the 8 post-therapy scan negative patients, only one showed fall in serum calcitonin level, while others showed a rise at 3 months post-therapy. Mean duration between the two scans in the patients with positive post-therapy scan was 131 days, while that in the negative group was 132 days. No significant difference between the two groups was apparent as far as age, sex, and site of disease is concerned. There was no intra-patient discordance. Either all lesions showed uptake or no lesion showed uptake in Fifteen MTC patients (13 male, 2 female; age range: 22-74 years) with a positive 68Ga-DOTANOC PET-CT scan were recruited for 177Lu-DOTATATE therapy. Patient characteristics are detailed in [Table 1] and [Table 2]. Total of 150 mCi of 177Lu-DOTATATE was administered as first therapeutic dose to each patient. Cumulative dose of 600-800 mCi of 177Lu-DOTATATE was infused to each post-therapy scan positive patients who showed good uptake on planar images, over 5-6 cycles (10-12 weeks of interval between each cycle). Eight of 15 (53.3%) patients showed no or poor uptake (defined as no or faint tracer uptake seen on planar images) of 177Lu-DOTATATE and were not given further radionuclide therapy, while 7 patients (46.7%) showed good uptake of 177Lu-DOTATATE and were scheduled for further therapy. Mean serum calcitonin was 7136 pg/ml (median, 3257 pg/ml, range: 245-29406 pg/ml). Mean percentage reduction in serum calcitonin of seven DOTATATE positive patients was 36.93 at 3 months post-therapy. Of the 8 post-therapy scan negative patients, only one showed fall in serum calcitonin level, while others showed a rise at 3 months post-therapy. Mean duration between the two scans in the patients with positive post-therapy scan was 131 days, while that in the negative group was 132 days. No significant difference between the two groups was apparent as far as age, sex, and site of disease is concerned. There was no intra-patient discordance. Either all lesions showed uptake or no lesion showed uptake in post-therapy scan. Preclinical data indicates that 68 Ga-DOTA-TOC shows a very high affinity for somatostatin receptors (sstr) 2 and 5, while DOTA-TATE has high affinity for receptor subtype 2 mainly. [1] Wild et al. developed [ 111 In, 90 Y-DOTA]-1-Nal 3 -octreotide ( 111 In, 90 Y-DOTA-NOC), which shows high binding affinity to sstr2, sstr3, and sstr5. [2] Different receptor affinity profile of DOTA-NOC and DOTA-TATE could be reason for non-concentration of 177Lu-DOTATATE in MTC. These findings point towards selective somatostatin receptor type 3 and 5 expression rather than type 2 in a subset of MTC patients. Another speculation, although unlikely, could be the occurrence of stunning due to the pre-therapy scan. This issue of discordance may be resolved by using same ligands in the diagnostic scan and therapeutic scan. Also, the same ligand hypothesis needs to be tested and results compared with the current findings. The small sample size in the current patient cohort ruled out any effective statistical analysis.{Table 1}{Table 2}

References

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2Wild D, Schmitt JS, Ginj M, Mäcke HR, Bernard BF, Krenning E, et al. DOTA-NOC, a high-affinity ligand of somatostatin receptors subtypes 2, 3 and 5 for labelling with various radiometals. Eur J Nucl Med Mol Imaging 2003;30:1338-47.