Neutron versus photon radiotherapy for local control in inoperable breast cancer.
OBJECTIVE
By virtue of their high linear energy transfer (LET) characteristics the biologic effectiveness of neutrons is less dependent on tissue oxygenation tension and cell cycle phase as compared to that with photons. Hence, an improved clinical benefit is to be expected predominantly in large, hypoxic and slowly growing tumors. Since a short course of radiotherapy is required for clinical reasons, it prompted the authors to initiate a randomly controlled trial on locally advanced breast cancer.


METHODS
Between 1996 and 1999, 27 patients with locally advanced breast cancer were irradiated with photons (60 Gy, 30 fractions; 8 MV, (60)Co) or neutrons (18 Gy, twelve fractions; 66 MeV(p-->Be)). The mean tumor diameters were 699 +/- 399 ml for the photon group and 1,097 +/- 831 ml in the neutron group.


RESULTS
After a mean follow-up period of 21.5 months tumor involution was evaluated in 22 patients. Partial and complete remissions were registered in 6/10 patients of the photon group and 5/12 patients of the neutron group. Late grade 3-4 morbidity according to RTOG definition was scored in 5/10 patients in the photon group and in 6/12 patients in the neutron group. With regard to tumor control and late radiation morbidity no differences between the two treatment arms were observed.


CONCLUSIONS
The underlying data indicate that no benefit is to be expected from neutron therapy in breast cancer.
Murray
Elizabeth M
EM
Radiation Oncology Department, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa. emurray@curie.uct.ac.za
Werner
I Dudley
ID
Schmitt
Gerd
G
Stannard
Clare
C
Gudgeon
Anne
A
Wilson
Jennifer
J
Fredericks
Shaheeda
S
McEvoy
Elene
E
Nel
Elizabeth
E
Hunter
Alistair
A
Slabbert
Jacobus P
JP
Langman
Gerald
G
D000328:Adult; D001943:Breast Neoplasms / Q000401:mortality* / Q000532:radiotherapy* / Q000601:surgery; D015984:Causality; D015897:Comorbidity; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality* / Q000532:radiotherapy* / Q000601:surgery; D009502:Neutrons / Q000627:therapeutic use*; D010166:Palliative Care / Q000706:statistics & numerical data*; D017785:Photons / Q000627:therapeutic use*; D011832:Radiation Injuries / Q000453:epidemiology; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D013019:South Africa / Q000453:epidemiology; D016019:Survival Analysis; D016896:Treatment Outcome