Radiotherapy for low-grade gastric marginal zone lymphoma: a retrospective study

Benefit of volumetric-modulated arc therapy over three-dimensional conformal radiotherapy for stage I-II extranodal marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue in the stomach: a dosimetric comparison

Purpose

To retrospectively analyze dosimetric parameters of volumetric-modulated arc therapy (VMAT) and three-dimensional conformal radiotherapy (3D-CRT) delivered to extranodal marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue in the stomach (gastric MALT lymphoma) to find out advantages of VMAT and conditions for definite benefits of VMAT.

Materials and Methods

Fifty patients with stage I-II gastric MALT lymphoma received VMAT (n = 14) or 3D-CRT (n = 36) between December 2005 and April 2018. Twenty-seven patients were categorized according to whether the planning target volume (PTV) overlaps kidney(s). Dosimetric parameters were analyzed by dose-volume histogram.

Results

Radiation dose to the liver was definitely lower with VMAT in terms of mean dose (p = 0.026) and V₁₅ (p = 0.008). The V₁₅ of the left kidney was lower with VMAT (p = 0.065). For those with PTV overlapping kidney(s), the left kidney V₁₅ was significantly lower with VMAT. Furthermore, the closer the distance between the PTV and kidneys, the less the left kidney V₁₅ with VMAT (p = 0.037). Delineation of kidney(s) by integrating all respiratory phases had no additional benefit.

conclusions

VMAT significantly increased monitor units, reduced treatment time and radiation dose to the liver and kidneys. The benefit of VMAT was definite in reducing the left kidney V₁₅, especially in geometrically challenging conditions of overlap or close separation between PTV and kidney(s).

Radiotherapy for gastric mucosa-associated lymphoid tissue lymphoma: dosimetric comparison and risk assessment of solid secondary cancer

Purpose

To determine the optimal radiotherapy technique for gastric mucosa-associated lymphoid tissue lymphoma (MALToma), we compared the dosimetric parameters and the risk of solid secondary cancer from scattered doses among anterior-posterior/posterior-anterior parallel-opposed fields (AP/PA), anterior, posterior, right, and left lateral fields (4_field), 3-dimensional conformal radiotherapy (3D-CRT) using noncoplanar beams, and intensity-modulated radiotherapy composed of 7 coplanar beams (IMRT_co) and 7 coplanar and noncoplanar beams (IMRT_non).

Materials and Methods

We retrospectively generated 5 planning techniques for 5 patients with gastric MALToma. Homogeneity index (HI), conformity index (CI), and mean doses of the kidney and liver were calculated from the dose-volume histograms. Applied the Biological Effects of Ionizing Radiation VII report to scattered doses, the lifetime attributable risk (LAR) was calculated to estimate the risk of solid secondary cancer.

Results

The best value of CI was obtained with IMRT, although the HI varied among patients. The mean kidney dose was the highest with AP/PA, followed by 4_field, 3D-CRT, IMRT_co, and IMRT_non. On the other hand, the mean liver dose was the highest with 4_field and the lowest with AP/PA. Compared with 4_field, the LAR for 3D-CRT decreased except the lungs, and the LAR for IMRT_co and IMRT_non increased except the lungs. However, the absolute differences were much lower than <1%.

Conclusion

Tailored RT techniques seem to be beneficial because it could achieve adjacent organ sparing with very small and clinically irrelevant increase of secondary solid cancer risk compared to the conventional techniques.

[Clinical characteristics and prognostic analysis of 90 patients with primary gastro-intestinal marginal zone lymphoma]

OBJECTIVE

To evaluate the clinical characteristics and prognostic factors of patients with primary gastro-intestinal marginal zone lymphoma (MALT).

METHODS

Retrospective analysis was performed in 90 patients diagnosed with primary gastro-intestinal MALT lymphoma clinical characteristics and survival analyses.

RESULTS

Among 90 patients, 78 cases were originated from the stomach and 12 cases with extra-gastric origin. Eighty patients were classified as low-risk (IPI score 0-2), and 10 patients high-risk (IPI score 3-5). Compared to gastric MALT patients, extra-gastric cases presented with higher IPI score (7.7% vs 33.3%, P=0.025) and higher Hp infection rate (50.0% vs 87.2%, P<0.01). Treatment options for low risk patients (IPI score 0-2) included Hp eradication, surgery, radiotherapy and chemotherapy. Chemotherapy could improve progression-free survival (PFS) in low-risk patients. For high-risk patients, those receiving chemotherapy had 100% 3-year overall survival (OS). Univariate analysis revealed that ECOG (P=0.006), Mussh-off staging (P=0.008), IPI score (P=0.000), elevated LDH (P=0.019) and chemotherapy (P=0.026) were correlated with PFS. Multivariate analysis showed that higher IPI score (IPI 3-5) (OR=8.325, 95% CI 3.171-21.853, P=0.000) and chemotherapy (OR=0.319, 95% CI 0.121-0.838, P=0.020) were independent prognostic factors for PFS. ECOG (≥ 2) was independent prognostic factor for OS (OR=5.092, 95%CI 1.005-25.788, P=0.049).

CONCLUSION

Primary gastro-intestinal MALT lymphoma was an indolent subtype of non-Hodgkin's lymphoma. Patients usually had low risk IPI and achieved long-term survival. Frontline therapy for low-risk patients was radiotherapy or Hp eradication, and chemotherapy for high-risk ones.

Clinical outcomes of radiation therapy for early-stage gastric mucosa-associated lymphoid tissue lymphoma

AIM: To evaluate the clinical outcomes of radiation therapy (RT) for early-stage gastric mucosa-associated lymphoid tissue lymphoma (MALToma).

METHODS: The records of 64 patients treated between 1998 and 2011 were analyzed retrospectively. For Helicobacter pylori (H. pylori)-positive patients (n = 31), chemotherapy or H. pylori eradication therapy was the initial treatment. In patients with failure after H. pylori eradication, RT was performed. For H. pylori-negative patients (n = 33), chemotherapy or RT was the first-line treatment. The median RT dose was 36 Gy. The target volume included the entire stomach and the perigastric lymph node area.

RESULTS: All of the patients completed RT without interruption and showed complete remission on endoscopic biopsy after treatment. Over a median follow-up period of 39 mo, the 5-year local control rate was 89%. Salvage therapy was successful in all relapsed patients. Secondary malignancies developed in three patients. The 5-year overall survival rate was 94%. No patient presented symptoms of moderate-to-severe treatment-related toxicities during or after RT.

CONCLUSION: Radiotherapy results in favorable clinical outcomes in patients with early-stage gastric MALToma who experience failure of H. pylori eradication therapy and those who are H. pylori negative.