Factors associated with radiation necrosis and intracranial control in patients treated with immune checkpoint inhibitors and stereotactic radiotherapy

BACKGROUND AND PURPOSE

Emerging data suggest immune checkpoint inhibitors (ICI) and stereotactic radiosurgery (SRS) or radiotherapy (SRT) may work synergistically, potentially increasing both efficacy and toxicity. This manuscript characterizes factors associated with intracranial control and radiation necrosis in this group.

MATERIALS AND METHODS

All patients had non-small cell lung cancer, renal cell carcinoma, or melanoma and were treated from 2013 to 2021 at two institutions with ICI and SRS/SRT. Univariate and multivariate analysis were used to analyze factors associated with local failure (LF) and grade 2+ (G2 + ) radiation necrosis.

RESULTS

There were 179 patients with 549 metastases. The median follow up from SRS/SRT was 14.7 months and the median tumor size was 7 mm (46 tumors ≥ 20 mm). Rates of LF and G2 + radiation necrosis per metastasis were 5.8% (32/549) and 6.9% (38/549), respectively. LF rates for ICI +/- 1 month from time of radiation versus not were 3% (8/264) and 8% (24/285) (p = 0.01), respectively. G2 + radiation necrosis rates for PD-L1 ≥ 50% versus < 50% were 17% (11/65) and 3% (5/203) (p=<0.001), respectively. PD-L1 ≥ 50% remained significantly associated with G2 + radiation necrosis on multivariate analysis (p = 0.03). Rates of intracranial failure were 54% (80/147) and 17% (4/23) (p = 0.001) for those without and with G2 + radiation necrosis, respectively.

CONCLUSIONS

PD-L1 expression (≥50%) may be associated with higher rates of G2 + radiation necrosis, and there may be improved intracranial control following the development of radiation necrosis. Administration of ICIs with SRS/SRT is overall safe, and there may be some local control benefit to delivering these concurrently.

Outcomes of surgical resection and intraoperative electron radiotherapy for patients with para-aortic recurrences of gastrointestinal and gynecologic malignancies

BACKGROUND

Para-aortic lymph node (PALN) metastases from primary pelvic malignancies are often treated with resection, but recurrence is common. We report toxicity and oncologic outcomes for patients with PALN metastases from gastrointestinal and gynecologic malignancies treated with resection and intraoperative electron radiotherapy (IORT).

METHODS

We retrospectively identified patients with recurrent PALN metastases who underwent resection with IORT. All patients were included in the local recurrence (LR) and toxicity analyses. Only patients with primary colorectal tumors were included in the survival analysis.

RESULTS

There were 26 patients with a median follow up of 10.4 months. The rate of para-aortic local control (LC) was 77% (20/26 patients) and the rate of any cancer recurrence was 58% (15/26 patients). Median time from surgery and IORT to any recurrence was 7 months. The LR rate for those with positive/close margins was 58% (7/12 patients) versus 7% (1/14 patients) for those with negative margins (p = 0.009). 15% (4/26 patients) developed surgical wound and/or infectious complications, 8% (2/26 patients) developed lower extremity edema, 8% (2/26 patients) experienced diarrhea, and 19% (5/26 patients) developed an acute kidney injury. There were no reported nerve injuries, bowel perforations, or bowel obstructions. For patients with primary colorectal tumors (n = 19), the median survival (OS) was 23 months.

CONCLUSIONS

We report favorable LC and acceptable toxicity for patients receiving surgical resection and IORT for a population that has historically poor outcomes. Our data show disease control rates similar to literature comparisons for patients with strong risk factors for LR, such as positive/close margins.

NCOG-05. A BRAIN METASTASES SURVIVAL MODEL USING AN ENSEMBLE TREE APPROACH

PURPOSE/OBJECTIVE(S)

The primary purpose of this study is to determine whether a machine learning approach can estimate survival in patients with brain metastases undergoing stereotactic radiosurgery or fractionated stereotactic radiotherapy (SRS/SRT). The secondary purpose is to identify covariates of importance.

MATERIALS/METHODS

Data were collected for 377 SRS/SRT treatments in 291 patients done between the years 2008-2021. If a patient was treated with more than one course of SRS/SRT within 30 days, they were counted only once. Twenty-five clinically-relevant variables were identified as covariates and the primary outcome of time from brain metastasis diagnoses to death was used to build a random survival forest model. Brain metastasis location was categorized as infratentorial, supratentorial, or both. An 80/20 split was used for training (n = 302) and test (n = 75) sets. Missing data points were imputed using a just-in-time adaptive tree approach. Minimal depth and variable importance (VIMP) approaches were used to identify prognostic factors. Model performance was assessed using time-dependent area under the receiver operating characteristics curve (tAUC).

RESULTS

Median survival time was 16 months. The most important variables according to minimal depth analysis (depth threshold 5.23) were Karnofsky Performance Status (KPS), extracranial status, age, insurance status, metastases volume, histology, number of metastases, and location. Error rate on the test set was 0.38. tAUC was found to increase continuously over time and at 6, 12, 24, and 36 months was 0.56, 0.63, 0.74, and 0.84 respectively.

CONCLUSION

An ensemble tree approach can provide good survival prediction for patients with brain metastases undergoing SRS/SRT. Model performance, as measured by tAUC, increases over time suggesting better predictive capability at longer time intervals. Future directions include collecting more data to increase model performance, comparing to other models, and validating with external data.

RADT-03. OUTCOMES OF PATIENTS WITH HER2-POSITIVE BREAST CANCER METASTATIC TO BRAIN TREATED WITH HER2-TARGETED SYSTEMIC THERAPY AND STEREOTACTIC RADIOSURGERY

OBJECTIVE

For patients with HER2-positive breast cancer metastatic to brain, HER2-directed systemic therapies are increasingly used with stereotactic radiosurgery (SRS). These include monoclonal antibodies such as trastuzumab (H) and pertuzumab (P), antibody-drug conjugates such as ado-trastuzumab emtansine (T-DM1), and tyrosine kinase inhibitors such as lapatinib. Limited data exist regarding appropriate timing with SRS and outcomes of this treatment regimen.

METHODS

A single-institution retrospective review collected clinical data on patients with breast cancer metastatic to brain who were treated with SRS from 2009-2020. Statistical analyses were performed using the Kaplan-Meier method and chi-square statistic.

RESULTS

Of 82 patients with breast cancer metastatic to brain treated with SRS, 33 (40%) were HER2-positive, 18 of whom were hormone receptor-positive. At brain metastasis diagnosis, 15 patients (45%) had &gt;1 intracranial metastasis (range 2-7), and the median brain metastasis maximal dimension was 2.0 cm. Fifteen patients had uncontrolled extracranial disease. After brain metastasis diagnosis, 9 patients (27%) were treated with systemic therapy first (T-DM1+/-HP, lapatinib+HP, chemotherapy+/-HP) followed by SRS at a median of 18.6 months after starting systemic therapy. Seven patients (21%) were treated with SRS first, followed by systemic therapy in 6 of these patients (multi-agent regimens, 4 including T-DM1 or lapatinib). Seventeen (52%) received concurrent systemic therapy and SRS (T-DM1+/-chemotherapy, lapatinib, HP, hormone therapy, chemotherapy). Median follow-up time was 21.1 months. Median overall survival was 24.8 months and not statistically different between treatment groups. Four patients (12%) developed symptomatic radionecrosis; 3 were on T-DM1 concurrent with SRS.

CONCLUSION

In this small patient sample, we noted favorable survival outcomes for patients with HER2-positive breast cancer metastatic to brain when treated with HER2-targeted therapies together with SRS. The sequence of systemic therapy and SRS does not appear to impact survival outcomes. Concurrent treatment with T-DM1 and SRS may be associated with higher rates of radionecrosis.

RADT-08. A VOLUMETRIC ANALYSIS OF STEREOTACTIC RADIOSURGERY LOW DOSE VOLUMES IN PREVENTING FUTURE BRAIN METASTASES

PURPOSE/OBJECTIVE(S)

Stereotactic radiosurgery (SRS), compared to whole brain radiotherapy is limited in its ability to prevent development of brain metastases in untreated areas. The purpose of this study is to assess whether low-dose volumes delivered to uninvolved regions of the brain during SRS can reduce the risk of developing brain metastases in those regions.

MATERIALS AND METHODS

Data were collected for 69 patients with brain metastases who were treated with SRS at least two occasions. The regions of uninvolved brain receiving a high, intermediate, and low dose of incidental radiotherapy were defined as the volume receiving at least 10, 5, and 2.5 Gy if the prescribed dose was &lt; 25 Gy (1-3 fraction plans) or the volume receiving at least 15, 7.5, and 5 Gy if the prescribed dose was ≥ 25 Gy (5 fraction plans). A second round metastasis was considered to occur within a given dose level if 20% or more of the tumor was found within that dose level. Probabilities were calculated based on the volume of each dose level as a percentage of total brain volume and were used to estimate the expected number of cases with at least one metastasis occurring in each dose level.

RESULTS

The average number of metastases treated in both rounds of SRS was two. The expected and observed number of cases with at least one second round metastasis were 0 and 2 for the high dose level (p=0.151), 7 and 3 for the intermediate dose level (p=0.018), and 17 and 11 for the low dose level (p=0.094).

CONCLUSION

We observed fewer than expected new metastases within prior SRS low dose levels based on volumetric probabilities, though this difference was only significant for the intermediate dose level. This suggests that low dose volumes from SRS may provide benefit in preventing future regional metastases.

Pediatric to Adult Transition in Sickle Cell Disease: Survey Results from Young Adult Patients

BACKGROUND/AIMS

We surveyed sickle cell disease (SCD) patients who transitioned from pediatric care at Texas Children's Hematology Center (TCHC) to adult care to determine the characteristics of patients with an adult SCD provider, continuation rates of pre-transition therapies, and patient perceptions of the transition process.

METHODS

A cross-sectional study was conducted by telephone survey of 44 young adults with SCD, aged 19-29 years, who transitioned from TCHC to adult care within the last 15 years.

RESULTS

Findings of the 23-item questionnaire revealed that transitioned patients with current adult providers (68.2%) were more likely to have seen a provider within 6 months of transition (p = 0.023) and to have been on hydroxyurea and/or monthly blood transfusions pre-transition (p = 0.021) than transitioned patients without a provider; 83% of patients on pre-transition hydroxyurea reported continuing hydroxyurea after transition. Transition challenges included inadequate preparation, difficulty finding knowledgeable adult providers, and lack of healthcare insurance/coverage.

CONCLUSION

Transition to adult providers is predicted by establishing care with an adult SCD provider within 6 months of transition and being on pre-transition disease-modifying therapy. Transition may be improved if pediatric hematology centers assist and verify adult provider contact within 6 months of transition and engage patients of all disease severity during transition.

A retrospective evaluation of furosemide and mannitol for prevention of cisplatin-induced nephrotoxicity

WHAT IS KNOWN AND OBJECTIVE

Nephrotoxicity is a recognized side effect of cisplatin chemotherapy. However, the optimal strategy for preventing cisplatin-induced nephrotoxicity, if any, remains unclear. The primary objective for this study was to determine whether mannitol or furosemide provides better nephroprotection when administered with hydration prior to weekly, low-dose cisplatin concurrently with whole pelvic radiotherapy.

METHODS

Clinical data were abstracted from all women who underwent chemoradiation for FIGO IB2-IVA cervical cancer at a regional safety net health system between January 2009 and December 2014. Creatinine clearance was estimated using the IDMS-traceable MDRD Study Equation. Descriptive statistics were used to summarize patient demographics. Cox proportional hazard models were used to identify factors associated with hypomagnesemia and survival.

RESULTS AND DISCUSSION

A total of 133 women received 656 weekly doses of single-agent cisplatin (40 mg/m² ) concomitant with whole pelvic radiation. Furosemide (20 mg) was administered intravenously prior to 341 cisplatin doses, whereas mannitol (24 g) was administered prior to 315 doses. Significant magnesium wasting was observed after the second weekly cisplatin infusion regardless of whether furosemide or mannitol was utilized. Repetitive low-dose cisplatin infusion had no impact on measured levels of serum creatinine or estimated glomerular filtration rate. Prior history of hypertension, diabetes mellitus, hepatitis C infection and acute gastrointestinal toxicity were each associated with early onset of hypomagnesemia.

WHAT IS NEW AND CONCLUSIONS

Repetitive administration of low-dose cisplatin concurrent with whole pelvic radiation is associated with magnesium wasting. However, choice of diuretic with pretreatment hydration had no significant impact on the severity of this adverse effect.

Chemical recognition and binding kinetics in a functionalized tunnel junction

4(5)-(2-mercaptoethyl)-1H-imidazole-2-carboxamide is a molecule that has multiple hydrogen bonding sites and a short flexible linker. When tethered to a pair of electrodes, it traps target molecules in a tunnel junction. Surprisingly large recognition-tunneling signals are generated for all naturally occurring DNA bases A, C, G, T and 5-methyl-cytosine. Tunnel current spikes are stochastic and broadly distributed, but characteristic enough so that individual bases can be identified as a tunneling probe is scanned over DNA oligomers. Each base yields a recognizable burst of signal, the duration of which is controlled entirely by the probe speed, down to speeds of 1 nm s -1, implying a maximum off-rate of 3 s -1 for the recognition complex. The same measurements yield a lower bound on the on-rate of 1 M -1 s -1. Despite the stochastic nature of the signals, an optimized multiparameter fit allows base calling from a single signal peak with an accuracy that can exceed 80% when a single type of nucleotide is present in the junction, meaning that recognition-tunneling is capable of true single-molecule analysis. The accuracy increases to 95% when multiple spikes in a signal cluster are analyzed.

A path integral study of the role of correlation in exchange coupling of spins in double quantum dots and optical lattices

We explore exchange coupling of a pair of spins in a double dot and in an optical lattice, using the frequency of exchanges in a bosonic path integral, evaluated using Monte Carlo simulation. The algorithm gives insights into the role of correlation through visualization of two-particle probability densities, instantons, and the correlation hole. We map the problem to the Hubbard model and see that exchange and correlation renormalize the model parameters, dramatically reducing the effective on-site repulsion at larger separations.

Theory of excitonic spectra and entanglement engineering in dot molecules

We present results of correlated pseudopotential calculations of an exciton in a pair of vertically stacked InGaAs/GaAs dots. Competing effects of strain, geometry, and band mixing lead to many unexpected features missing in contemporary models. The first four excitonic states are all optically active at small interdot separation, due to the broken symmetry of the single-particle states. We quantify the degree of entanglement of the exciton wave functions and show its sensitivity to interdot separation. We suggest ways to spectroscopically identify and maximize the entanglement of exciton states.

Tocolysis with advanced cervical dilatation

OBJECTIVE

To assess the feasibility and potential benefit of delaying delivery in women with advanced preterm labor.

METHODS

Two hundred fifty-seven gravidas with intact membranes and preterm labor at cervical dilatations of at least 3 cm were studied. Women were excluded if they had premature rupture of membranes, gestational age less than 24 or more than 35.9 weeks, complete cervical dilatation, severe hemorrhage, chorioamnionitis, and triplets or higher-order gestations. Management consisted of tocolysis with intravenous magnesium sulfate as the primary agent, antenatal steroids, antibiotics, and amniocentesis. The primary endpoint was delay to delivery interval. Statistical analyses by cervical dilatation were performed using the Pearson chi2 test and a nonparametric test of trend.

RESULTS

Eighty-one percent of pregnancies were referrals in utero from outlying hospitals. Delivery was delayed 24 hours or longer in 74% and beyond 48 hours in 60% of cases. Among 229 women who delivered at our center, 21% remained undelivered after 1 week. Evaluating delay as a function of cervical dilatation, trend analysis found a highly significant inverse relationship (P < .001). Among women dilated 5 cm, 46% delivered beyond 48 hours. Among those dilated 6 cm or more, 19% delivered beyond 48 hours. Mild pulmonary edema developed in five percent, and all responded promptly to medical interventions. Chorioamnionitis developed in eight percent.

CONCLUSION

Delaying delivery 24-48 hours to allow antenatal steroid use or other interventions is possible in women with advanced preterm labor.

Preterm labor, placental abruption, and premature rupture of membranes in relation to maternal violence or verbal abuse

OBJECTIVE

The prevalence of preterm labor (PTL) in prenatal populations has been estimated to be from 6.9 to 10.0%. It has been suggested that violence during pregnancy may be associated with an increase in antenatal complications. The hypothesis is that physical violence and verbal abuse in pregnancy lead to increased risk of PTL.

METHODS

A cohort of 636 women attending the Adult Obstetrical Clinic for their first prenatal visit, between December 1989 and September 1990, were approached; 567 women enlisted as study participants. Study participants were interviewed 3 times during the course of their prenatal care, and 401 participants successfully completed their third prenatal interviews. Violence data were obtained during the third interview. Obstetrical and neonatal outcome data were obtained by abstracting the maternal and neonatal medical records.

RESULTS

When stratified by levels of violence, women who experienced moderate or severe violence had incidences of PTL of 15.4 and 17.2%, respectively. Chi-square test for homogeneity revealed a significant difference among these groups.

CONCLUSIONS

In our cohort of women, serious acts of verbal abuse and physical violence occurred with significant frequency. PTL was strongly correlated with increasing acts of violence with 4.1 times greater risk of PTL in women who experienced severe violence as compared to those who experienced no maternal abuse.

Medical malpractice involving radiologic colon examinations: a review of 38 recent cases

OBJECTIVE

Our purposes were to determine the causes of malpractice claims against radiologists performing contrast examinations of the colon and to design strategies to reduce litigation and diminish patient morbidity.

MATERIALS AND METHODS

Reports of malpractice claims were collected from legal journals and databases between 1985 and 1994. For this period, 38 plaintiffs raised 52 allegations of malpractice that involved radiologists performing barium or Hypaque (meglumine diatrizoate; Winthrop Pharmaceuticals, New York, NY) colon examinations. For the 38 cases, 18 plaintiffs for decedents alleged that failure to diagnose colorectal cancer by barium enema examination caused delay in treatment and the patient's death. Eighteen plaintiffs alleged that improper performance of barium (17 cases) or meglumine diatrizoate (one case) colon examinations caused perforation of the colon, resulting in significant morbidity (15 cases) or death (three cases). Miscellaneous causes for malpractice claims were recorded in two cases.

RESULTS

In 18 cases of failure to diagnose colorectal cancer, the initial radiographs were interpreted as follows: normal findings in 14 cases, diverticulosis in one case, and spastic bowel in two cases; in the remaining case, colon cancer was missed because of nonopacification of the cecum. In retrospect, 17 of 18 colorectal cancers were visualized. The delay in the diagnosis of colorectal cancer ranged from 5 to 72 months. Missed colorectal cancers occurred in the cecum (two cases), transverse colon (two cases), rectosigmoid area (nine cases), or unspecified area (five cases). In 18 cases of colon perforation, the site was the cecum (one case), transverse colon (one case), extraperitoneal rectum (seven cases), rectosigmoid area (one case), colostomy stoma (two cases), or unspecified area (six cases). One patient experienced anaphylactic shock that required hospitalization. One underwent unnecessary surgery because barium enema films showing colon cancer were mislabeled with her name.

CONCLUSION

On the basis of our analyses of malpractice claims, we suggest strategies to prevent medicolegal litigation. Strategies include communicating with the patient about the type and indications of the barium enema examination, performing digital rectal examinations on all patients to detect distal rectal lesions or strictures, recognizing colon perforation, and obtaining immediate surgical consultation if colon perforation occurs. The number of missed colon cancers may be reduced by reading twice or reviewing at a later time all barium enema examinations.