Chemotherapy alone versus chemotherapy plus radiotherapy for adults with early stage Hodgkin lymphoma

Oliver Blank, Bastian von Tresckow, Ina Monsef, Lena Specht, Andreas Engert, Nicole Skoetz

Combined modality treatment consisting of chemotherapy followed by localised radiotherapy is the standard treatment for patients with early stage Hodgkin lymphoma (HL). However, due to long- term adverse effects such as secondary malignancies the role of radiotherapy has been questioned recently and some clinical study groups advocate chemotherapy only for this indication. To assess the effects of chemotherapy alone compared to chemotherapy plus radiotherapy in adults with early stage HL . For the or i ginal version of this review, we searched MEDLINE, Embase and CENTRAL as well as conference proceedings (American Society of Hematology, American Society of Clinical Oncology and International Symposium of Hodgkin Lymphoma) from January 1980 to November 2010 for randomised controlled trials (RCTs) comparing chemotherapy alone versus chemotherapy regimens plus radiotherapy. For the updated review we searched MEDLINE, CENTRAL and conference proceedings to December 2016. We included RCTs comparing chemotherapy alone with chemotherapy plus radiotherapy in patients with early stage HL. We excluded trials with more than 20% of patients in advanced stage. As the value of radiotherapy in addition to chemotherapy is still not clear, we also compared to more cycles of chemotherapy in the control arm. In this updated review, we also included a second comparison evaluating trials with varying numbers of cycles of chemotherapy between intervention and control arms, same chemotherapy regimen in both arms assumed. We excluded trials evaluating children only, therefore only trials involving adults are included in this updated review. Two review authors independently extracted data and assessed the quality of trials. We contacted study authors to obtain missing information. As effect measures we used hazard ratios (HR) for overall survival (OS) and progression-free survival (PFS) and risk ratios (RR) for response rates. Since not all trials reported PFS according to our definitions, we evaluated all similar outcomes (e.g. event-free survival) as PFS/tumour control. Our search led to 5518 potentially relevant references. From these, we included seven RCTs in the analyses involving 2564 patients. In contrast to the first version of this review including five trials, we excluded trials randomising children. As a result, we excluded one trial from the former analyses and we identified three new trials.Five trials with 1388 patients compared the combination of chemotherapy alone and chemotherapy plus radiotherapy, with the same number of chemotherapy cycles in both arms. The addition of radiotherapy to chemotherapy has probably little or no difference on OS (HR 0.48; 95% confidence interval (CI) 0.22 to 1.06; P = 0.07, moderate- quality evidence), however two included trials had potential other high risk of bias due to a high number of patients not receiving planned radiotherapy. After excluding these trials in a sensitivity analysis, the results showed that the combination of chemotherapy and radiotherapy improved OS compared to chemotherapy alone (HR 0.31; 95% CI 0.19 to 0.52; P <0.00001, moderate- quality evidence). In contrast to chemotherapy alone the use of chemotherapy and radiotherapy improved PFS (HR 0.42; 95% CI 0.25 to 0.72; P = 0.001; moderate- quality evidence). Regarding infection- related mortality (RR 0.33; 95% CI 0.01 to 8.06; P = 0.5; low- quality evidence), second cancer- related mortality (RR 0.53; 95% CI 0.07 to 4.29; P = 0.55; low- quality evidence) and cardiac disease- related mortality (RR 2.94; 95% CI 0.31 to 27.55; P = 0.35;low- quality evidence), there is no evidence for a difference between the use of chemotherapy alone and chemotherapy plus radiotherapy. For complete response rate (CRR) (RR 1.08; 95% CI 0.93 to 1.25; P = 0.33; low- quality evidence), there is also no evidence for a difference between treatment groups.Two trials with 1176 patients compared the combination of chemotherapy alone and chemotherapy plus radiotherapy, with different numbers of chemotherapy cycles in both arms. OS is reported in one trial only, the use of chemotherapy alone (more chemotherapy cycles) may improve OS compared to chemotherapy plus radiotherapy (HR 2.12; 95% CI 1.03 to 4.37; P = 0.04; low- quality evidence). This trial also had a potential other high risk of bias due to a high number of patients not receiving planned therapy. There is no evidence for a difference between chemotherapy alone and chemotherapy plus radiotherapy regarding PFS (HR 0.42; 95% CI 0.14 to 1.24; P = 0.12; low- quality evidence). After excluding the trial with patients not receiving the planned therapy in a sensitivity analysis, the results showed that the combination of chemotherapy and radiotherapy improved PFS compared to chemotherapy alone (HR 0.24; 95% CI 0.070 to 0.88; P = 0.03, based on one trial). For infection- related mortality (RR 6.90; 95% CI 0.36 to 132.34; P = 0.2; low- quality evidence), second cancer- related mortality (RR 2.22; 95% CI 0.7 to 7.03; P = 0.18; low- quality evidence) and cardiac disease-related mortality (RR 0.99; 95% CI 0.14 to 6.90; P = 0.99; low-quality evidence), there is no evidence for a difference between the use of chemotherapy alone and chemotherapy plus radiotherapy. CRR rate was not reported. This systematic review compared the effects of chemotherapy alone and chemotherapy plus radiotherapy in adults with early stage HL .For the comparison with same numbers of chemotherapy cycles in both arms, we found moderate- quality evidence that PFS is superior in patients receiving chemotherapy plus radiotherapy than in those receiving chemotherapy alone. The addition of radiotherapy to chemotherapy has probably little or no difference on OS . The sensitivity analysis without the trials with potential other high risk of bias showed that chemotherapy plus radiotherapy improves OS compared to chemotherapy alone.For the comparison with different numbers of chemotherapy cycles between the arms there are no implications for OS and PFS possible, because of the low quality of evidence of the results.