Effect of intermittent fasting with or without caloric restriction on prostate cancer growth and survival in SCID mice.
BACKGROUND
Caloric restriction (CR) delays cancer growth in animals, though translation to humans is difficult. We hypothesized intermittent fasting (i.e., intermittent extreme CR), may be better tolerated and prolong survival of prostate cancer (CaP) bearing mice.


METHODS
We conducted a pilot study by injecting 105 male individually-housed SCID mice with LAPC-4 cells. When tumors reached 200 mm(3), 15 mice/group were randomized to one of seven diets and sacrificed when tumors reached 1,500 mm(3): Group 1: ad libitum 7 days/week; Group 2: fasted 1 day/week and ad libitum 6 days/week; Group 3: fasted 1 day/week and fed 6 days/week via paired feeding to maintain isocaloric conditions to Group 1; Group 4: 14% CR 7 days/week; Group 5: fasted 2 days/week and ad libitum 5 days/week; Group 6: fasted 2 day/week and fed 5 days/week via paired feeding to maintain isocaloric conditions to Group 1; Group 7: 28% CR 7 days/week. Sera from mice at sacrifice were analyzed for IGF-axis hormones.


RESULTS
There were no significant differences in survival among any groups. However, relative to Group 1, there were non-significant trends for improved survival for Groups 3 (HR 0.65, P = 0.26), 5 (0.60, P = 0.18), 6 (HR 0.59, P = 0.16), and 7 (P = 0.59, P = 0.17). Relative to Group 1, body weights and IGF-1 levels were significantly lower in Groups 6 and 7.


CONCLUSIONS
This exploratory study found non-significant trends toward improved survival with some intermittent fasting regimens, in the absence of weight loss. Larger appropriately powered studies to detect modest, but clinically important differences are necessary to confirm these findings.
Buschemeyer
W Cooper
WC
Division of Urology, and the Duke Prostate Center, Department of Surgery, Duke University Medical Center, Durham, North Carolina 27710, USA.
Klink
Joseph C
JC
Mavropoulos
John C
JC
Poulton
Susan H
SH
Demark-Wahnefried
Wendy
W
Hursting
Stephen D
SD
Cohen
Pinchas
P
Hwang
David
D
Johnson
Tracy L
TL
Freedland
Stephen J
SJ
D000818:Animals; D001823:Body Composition / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D048708:Cell Growth Processes / Q000502:physiology; D005215:Fasting / Q000502:physiology*; D018969:Insulin-Like Growth Factor Binding Proteins / Q000097:blood; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D051379:Mice; D016513:Mice, SCID; D010865:Pilot Projects; D016016:Proportional Hazards Models; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology*; D011897:Random Allocation; D016019:Survival Analysis
D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I