The impact of radiotherapy dose and other treatment-related and clinical factors on in-field control in stage I and II non-Hodgkin's lymphoma.
OBJECTIVE
To assess local (in-field) disease control, identify potential prognostic factors, and elucidate the optimal radiotherapy dose in various clinical settings of Stage I and II non-Hodgkin's lymphoma (non-CNS).


METHODS
A total of 285 consecutive patients with Stage I and II non-Hodgkin's lymphoma were treated with curative intent, including 159 with radiotherapy (RT) alone and 126 with combined-modality therapy (CMT). Of these, 72 patients had low-grade lymphomas (LGL), 92 had intermediate or high-grade lymphomas (I/HGL), and 21 had unclassified lymphomas. Clinical and treatment variables with potential prognostic significance for in-field disease control, freedom from relapse (FFR), and absolute survival (AS) were evaluated by univariate and multivariate analyses.


RESULTS
The 5-, 10-, and 20-year actuarial AS rates were 73%, 46%, and 33% for patients with LGL and 64%, 44%, and 18% for patients with I/HGL, respectively. The 5-, 10-, and 20-year actuarial FFR rates were 62%, 59%, and 49% for patients with LGL and 66%, 57%, and 57% for patients with I/HGL, respectively. Significant prognostic factors identified by the multivariate analysis were age, tumor size, and histology for AS; tumor size and treatment for FFR; and only tumor size for in-field disease control. There were 95 total failures, with only 12 occurring infield. Most failures (65%) were in contiguous unirradiated sites. All 4 in-field failures in patients with LGL occurred after RT doses < 30 Gy, although none occurred in 10 patients with small-volume LGL of the orbit treated with doses < 30 Gy. The 8 in-field failures in patients with I/HGL were distributed evenly throughout the RT dose range; 5 occurred in patients treated with CMT, all with tumors > 6 cm, and 4 with less than a complete response (CR) to chemotherapy.


CONCLUSIONS
Our analysis suggests that the overwhelming problem in the treatment of non-Hodgkin's lymphoma is not in-field failure but, rather, failure in contiguous unirradiated sites. A dose of 20-25 Gy may be sufficient for small-volume LGL of the orbit. A dose of 30 Gy is sufficient for LGL in general, as well as for patients with nonbulky (< or = 6 cm) I/HGL treated with CMT who have a CR. However, patients with I/HGL treated with CMT for tumors > 6 cm and/or without a CR may benefit from doses > or = 40 Gy.
Kamath
S S
SS
Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, USA.
Marcus
R B
RB
Lynch
J W
JW
Mendenhall
N P
NP
D000206:Actuarial Analysis; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D003131:Combined Modality Therapy; D003520:Cyclophosphamide / Q000008:administration & dosage; D004317:Doxorubicin / Q000008:administration & dosage; D005260:Female; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000188:drug therapy* / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011241:Prednisone / Q000008:administration & dosage; D011344:Procarbazine / Q000008:administration & dosage; D011379:Prognosis; D011879:Radiotherapy Dosage; D012008:Recurrence; D015996:Survival Rate; D014750:Vincristine / Q000008:administration & dosage
D011344:Procarbazine; D014750:Vincristine; D004317:Doxorubicin; D003520:Cyclophosphamide; D011241:Prednisone