Single high dose intraoperative electrons for advanced stage pancreatic cancer: phase I pilot study

Late gastrointestinal tissue effects after hypofractionated radiation therapy of the pancreas

BACKGROUND

To consolidate literature reports of serious late gastrointestinal toxicities after hypofractionated radiation treatment of pancreatic cancer and attempt to derive normal tissue complication probability (NTCP) parameters using the Lyman-Kutcher-Burman model.

METHODS

Published reports of late grade 3 or greater gastrointestinal toxicity after hypofractionated treatment of pancreatic cancer were reviewed. The biologically equivalent dose in 1.8 Gy fractions was calculated using the EQD model. NTCP parameters were calculated using the LKB model assuming 1-5% of the normal tissue volume was exposed to the prescription dose with α/β ratios of 3 or 4.

RESULTS

A total of 16 human studies were examined encompassing a total of 1160 patients. Toxicities consisted of ulcers, hemorrhages, obstructions, strictures, and perforations. Non-hemorrhagic and non-perforated ulcers occurred at a rate of 9.1% and were the most commonly reported toxicity. Derived NTCP parameter ranges were as follows: n = 0.38-0.63, m = 0.48-0.49, and TD50 = 35-95 Gy. Regression analysis showed that among various study characteristics, dose was the only significant predictor of toxicity.

CONCLUSIONS

Published gastrointestinal toxicity reports after hypofractionated radiotherapy for pancreatic cancer were compiled. Median dose was predictive of late grade ≥ 3 gastrointestinal toxicity. Preliminary NTCP parameters were derived for multiple volume constraints.

Is there a role for advanced radiation therapy technologies in the treatment of pancreatic adenocarcinoma?

Pancreatic cancer remains a highly challenging problem in oncology. Oncologists continue to search for therapies that are more effective than those currently available to improve on the existing poor treatment results. Persistence of both systemic and local disease causes high rates of morbidity and mortality for patients. Radiation continues to play a role in the treatment of pancreatic cancer, in both the adjuvant and locally advanced settings. Efforts to improve on the results of radiotherapy have led to the use of new and improved technologies. This review discusses a variety of these technological improvements and their current and potential future roles in the clinic.

Phase III trial of radiosensitizer PR-350 combined with intraoperative radiotherapy for the treatment of locally advanced pancreatic cancer

A randomized, controlled trial was conducted to clarify the effect of novel radiosensitizer, PR-350, accompanied by intraoperative radiology (IOR) on locally advanced pancreatic cancer. Between July 1999 and March 2002, 48 patients were enrolled in this clinical trial and received either PR-350 or placebo. Any differences between the PR-350 group (n = 22) and control group (n = 25) were not statically significant. All patients were evaluated, and none of them showed toxicity, with the exception of 1 patient from the control group, and the PR-350 compound was considered to be safe. The efficacy of IOR with PR-350 was evaluated using CT examination. The committee responsible for evaluating efficacy reported that 47.4% of the PR-350 group showed the effective response, compared with 21.7% of the control group (P = 0.1067, Fisher analysis). At 6 months following treatment, the tumor mass reduction rate in the PR-350 group was significantly improved (P = 0.0274). By the time of the last follow-up in July 2003, 17 PR-350 patients and 24 control patients group had died of the disease. The median survival period of the PR-350 group was thus 318.5 days and that of the control group is 303.0 days. One-year survival rates of the PR-350 group and control group were 36.4% and 32.0%, respectively. Although the PR-350 group did not demonstrate significantly better survival than the control group, 4 of 22 PR-350 patients were still living more than 2 years after the end of the trial, compared with only 1 of 25 patients from the control group. The mechanism of this increased therapeutic response to radiotherapy using PR-350 must be clarified to establish more effective strategy for pancreatic cancer treatment.

Feasibility and efficacy of high dose conformal radiotherapy for patients with locally advanced pancreatic carcinoma

BACKGROUND

The feasibility and efficacy of high dose conformal radiotherapy were examined in the treatment of patients with locally advanced, unresectable pancreatic carcinoma.

METHODS

Forty-four patients with pathologically confirmed, unresectable pancreatic adenocarcinoma without distant metastases were treated in a Phase II study. The patients received three-dimensional, planned, high dose conformal radiotherapy (70-72 grays). Toxicity was scored according to the World Health Organization criteria. Follow-up time ranged from 7 months to 25 months (median, 9 months).

RESULTS

The treatment was feasible. Forty-one patients received the intended total dose. Treatment was never stopped because of toxicity. Acute toxicity was mainly Grade 1 and Grade 2 (in 70% and 57% of patients, respectively), whereas Grade 3 toxicity was seen in 9% of patients. One fatal event occurred that was not treatment related. Late Grade 3 and Grade 4 gastrointestinal toxicity was seen in 3 patients and 2 patients, respectively. Late (Grade 5) gastrointestinal bleeding was observed in 3 patients, 2 of whom had local tumor progression. At 3 months, reduction in tumor size was seen in 27% of patients, stable disease was seen in 20% of patients, and local disease progression was seen in 40% of patients. Ultimately, local disease progression was observed in 44% of patients. No true partial or complete responses were documented. The median survival from the time of diagnosis was 11 months (10 months from the start of radiotherapy). Seventeen of 25 patients (68%) experienced pain relief.

CONCLUSIONS

High dose conformal radiotherapy for the treatment of patients with locally advanced pancreatic carcinoma is feasible with acceptable toxicity. In case of pain, it can offer palliation. The efficacy of the treatment in terms of prolongation of life is not proven. Distant metastases remain the major problem.

Intraoperative electron beam radiation therapy: technique, dosimetry, and dose specification: report of task force 48 of the Radiation Therapy Committee, American Association of Physicists in Medicine

Intraoperative radiation therapy (IORT) is a treatment modality whereby a large single dose of radiation is delivered to a surgically open, exposed cancer site. Typically, a beam of megavoltage electrons is directed at an exposed tumor or tumor bed through a specially designed applicator system. In the last few years, IORT facilities have proliferated around the world. The IORT technique and the applicator systems used at these facilities vary greatly in sophistication and design philosophy. The IORT beam characteristics vary for different designs of applicator systems. It is necessary to document the existing techniques of IORT, to detail the dosimetry data required for accurate delivery of the prescribed dose, and to have a uniform method of dose specification for cooperative clinical trials. The specific charge to the task group includes the following: (a) identify the multidisciplinary IORT team, (b) outline special considerations that must be addressed by an IORT program, (c) review currently available IORT techniques, (d) describe dosimetric measurements necessary for accurate delivery of prescribed dose, (e) describe dosimetric measurements necessary in documenting doses to the surrounding normal tissues, (f) recommend quality assurance procedures for IORT, (g) review methods of treatment documentation and verification, and (h) recommend methods of dose specification and recording for cooperative clinical trials.

Intraoperative radiation therapy following pancreaticoduodenectomy

OBJECTIVE

To determine the morbidity and mortality of pancreaticoduodenectomy followed by electron-beam intraoperative radiation therapy (EB-IORT).

SUMMARY BACKGROUND DATA

Local recurrence following pancreaticoduodenectomy occurs in 50% to 90% of patients who undergo a potentially curative surgical resection for adenocarcinoma of the pancreatic head. To improve local disease control, a more aggressive retroperitoneal dissection has been combined with adjuvant EB-IORT.

METHODS

Forty-one patients with malignant neoplasms of the periampullary region underwent pancreaticoduodenectomy followed by EB-IORT between January 1989 and May 1992. EB-IORT was delivered in a dedicated operative suite, eliminating the need for patient relocation. Electron-beam energies of 6 to 12 MeV were used to deliver 10 to 20 Gy to the treatment field following resection but before pancreatic, biliary, and gastrointestinal reconstruction.

RESULTS

Median operative time was 9 hours, blood loss was 1 L, perioperative transfusion requirement was 2 units, and hospital stay was 20 days. One patient died of a postoperative myocardial infarction, and four patients required reoperation, one for an anastomotic leak. No patient failed to receive EB-IORT because of operative complications during the time period of this study.

CONCLUSION

Adjuvant EB-IORT after pancreaticoduodenectomy can be delivered safely, with low mortality and acceptable morbidity.

The influence of surgical margins on advanced cancer treated with intraoperative radiation therapy (IORT) and surgical resection

Intraoperative radiation therapy (IORT) has been used successfully in the treatment of malignancies, alone and as an adjunct to surgical resection. This study examined a single institution's experience with combined IORT and surgical resection in the treatment of advanced cancer. The records of 41 consecutive patients undergoing intraoperative radiation therapy (IORT) at the Fox Chase Cancer Center, from July 1987 through March 1990, were retrospectively reviewed. All patients had locally advanced disease, of whom 73% had failed previous multimodality therapy and 44% had undergone prior radiation therapy (XRT). The 2-year actuarial survival for the entire cohort was 72%. Disease-free survival was 47% at 1 year and 5% at 2 years. The only important prognostic factor predicting outcome was status of the surgical margin. Positive surgical margins decreased the 2-year actuarial survival from 100% to 59%, and increased the local failure rate from 21% to 52%. Margin status had no effect on the later development of metastatic disease. Higher IORT doses, field sizes > 7 cm, and multiple IORT fields were used for larger tumors and larger amounts of residual disease. These parameters alone did not correlate with improved local control. This analysis suggests the usefulness of aggressive surgical resection with IORT in extending survival for locally advanced or recurrent cancer. Negative margin status is the best predictor of a favorable outcome and should be used to select patients who may benefit from IORT. The use of radiation sensitizing agents should be explored in patients with positive margins, since in-field failure continues to be the major pattern of failure. IORT in conjunction with aggressive surgical resection should continue to be studied in prospective randomized clinical trials.

Effect of intraoperative radiation on the tensile strength of small bowel anastomoses

Increasing interest in the use of preoperative or intraoperative radiation therapy for cancer has led to concerns regarding tissue healing and integrity subsequent to treatment. This is especially so for intestinal anastomoses incorporating irradiated bowel, where poor healing may lead to anastomotic disruption and sepsis. One hundred thirty Sprague-Dawley rats were randomized into five groups as follows: both limbs, one limb, or neither limb of an anastomosis received 2,000 R of radiation intraoperatively. A fourth group had a segment of small bowel irradiated, with no anastomosis; a fifth group had the gut exposed by celiotomy. The control groups and all anastomoses underwent tensile strength measurements on the seventh postoperative day, with findings as follows: no anastomosis, no irradiation, 143.75 g; no anastomosis, irradiated, 114.50 g; anastomosis, no irradiation, 85.273 g; anastomosis, one limb irradiated, 78.100 g; anastomosis, both limbs irradiated, 59.00 g. There was no statistical difference in tensile strength of the anastomosis between when neither limb and when just one limb was irradiated. However, when both limbs were irradiated, the loss of strength was statistically significant (P = 0.002). Irradiation damage scores were assigned using Black et al.'s histologic scoring system. These scores were not significantly different between the irradiated segments. Inflammation and fibrosis scores for the anastomoses were also not significantly different. These results indicate that, in rats, anastomotic healing is impaired only when both limbs of the anastomosed intestine are irradiated. The normal strength of the anastomosis with only one limb irradiated cannot be explained by differences in inflammation, fibrosis, or radiation damage and is caused by an undetermined factor.

Arteriodigestive fistula: a complication associated with intraoperative and external beam radiotherapy following surgery for gastric cancer

Intestinal hemorrhage due to arteriodigestive fistula is described to be a rare and serious complication of radiotherapy. Three cases of this type of fistula in gastric cancer patients treated with gastrectomy, intraoperative electron boost (15 Gy), and fractionated external beam irradiation (46 Gy) are reported. Selective angiography is most helpful in the diagnosis and immediate surgery could be lifesaving. An attempt to explain the etiopathogenesis is made.

Intraoperative radiation therapy of pancreatic carcinoma: a report of RTOG-8505. Radiation Therapy Oncology Group

The Radiation Therapy Oncology Group in 1985 began a study of IORT plus external beam radiation therapy for patients with locally unresected, non-metastatic pancreatic cancer. Patients were treated with a combination of 2000 cGy of IORT and postoperative external beam radiation therapy to 5040 cGy in combination with IV 5-FU (500 mg/m2/day on the first 3 days of the external beam treatment). As patients were registered on study prior to exploration, it was expected that a number of patients would be excluded from further analysis at the time of surgery. Eighty-six patients were entered on study through 6/1/88 and analyzed through 4/90. Fifty-one patients were fully analyzable. Median survival time of the 51 patients was 9 months with an 18-month actuarial survival rate of 9%. Local control could not be adequately evaluated in this multi-institutional study. Major postoperative complications were not excessive and occurred in 12% of patients. Two patients had major late morbidity leading to death, one from duodenal bleeding and the second from biliary obstruction. Although this study does demonstrate the feasibility of IORT in a multi-institutional setting, it does not demonstrate any advantage of IORT over conventional therapy for this disease.

High dose, external beam and intraoperative radiotherapy in the treatment of resectable and unresectable pancreatic cancer

Ninety patients with pancreatic cancer were treated by external beam radiotherapy (EBRT) and/or intraoperative radiotherapy (IORT) with or without surgical resection of the tumor, and the results were compared with those of a historical control comprising 112 patients treated by surgery alone. At an early stage of this study, postoperative EBRT (50-60 Gy) or IORT (25-33 Gy) was given alone, but recently the two modalities have been combined. The combination of high doses of EBRT and IORT was well tolerated provided that the gastrointestinal tract was not irradiated during IORT. Although EBRT plus IORT appeared to yield better results than either EBRT or IORT alone, the difference was not significant on multivariate analysis, and patients receiving EBRT, IORT, or EBRT + IORT were grouped together. Patients receiving radiotherapy in addition to macroscopically curative surgery had a slightly longer median survival time (14 months) than those receiving curative surgery alone (10 months), but the 3-year survival rate was similar (21% vs. 19%). In patients who underwent noncurative resection, the median survival time was significantly longer for the irradiated group (12 months) than for the control group (6.5 months). Also, in patients with unresectable lesions but no distant metastases, irradiation prolonged the median survival time significantly (8 vs. 3.5 months). In this group, there was one 5-year survivor, who received EBRT of 55 Gy plus IORT of 30 Gy to his unresectable pancreatic body lesion. Patients with metastases were also treated for palliation of symptoms, but it was found that irradiation prolonged the median survival time even in such cases (4.5 vs. 2.5 months). Based on these results, we plan to use EBRT plus IORT in all pancreatic cancer patients with no metastases.

The prevalence and severity of late effects in normal rat duodenum following intraoperative irradiation

In humans, a portion of the duodenum is often at risk for radiation-induced complications following intraoperative radiation therapy for pancreatic carcinoma. To determine experimentally the prevalence and severity of late effects in the normal mammalian duodenum, 190 rats received single doses of 0, 15, 20, 25, 30, or 40 Gy orthovoltage X rays to temporarily exteriorized 3 cm circumferential segments of duodenum. The animals were killed 2, 6, 8, or 10 months later. Actuarial survival, change in body weight, and a radiation injury score based on eight histopathologic alterations were used as endpoints. Epithelial atypia, intestinal wall fibrosis, serosal thickening, and vascular sclerosis were the dominant histopathologic alterations at all dose levels throughout the 10-month observation period. The prevalence and severity of histologic radiation injury showed sigmoidal dose-response relationships with the plateaus starting at 20 Gy. Doses of 20 Gy or greater also resulted in a substantial loss of body weight and a high level of early deaths (20-80 days). All endpoints indicate that intraoperative doses of 20 Gy or greater are associated with unacceptable risks of late and irreversible complications.

Innovative techniques in radiation oncology. Clinical research programs to improve local and regional control in cancer

There is a growing importance in failure analysis in cancer management. In these analyses locoregional failure as the cause of death emerges as a significant problem in many tumor sites, e.g., head and neck cancer, gynecologic cancer, genitourinary cancer. Because of these data, the radiation oncology community has attributed high priority to research efforts to improve locoregional control. These efforts include the following: (1) brachytherapy alone or with external beam radiation therapy or surgery; (2) intraoperative radiation therapy; (3) hyperthermia with radiation therapy; (4) particle irradiation (protons, neutrons, stripped nuclei, and pions); and (5) routes of administration of the treatment, including infusional (intravenous) chemotherapy with radiation therapy, intraarterial monoclonal antibodies with radionuclides, and intraarterial chemotherapy with radiation therapy. Each area of investigation is discussed.

Management of pain in pancreatic cancer

Potentially useful modalities of pain control in pancreatic cancer include antitumor therapy, pharmacotherapy, celiac plexus block, splanchnic nerve block, intercostal nerve block, and psychological intervention. These modalities are often used concurrently in treating the multiple dimensions that affect pain. Although thorough assessments are lacking, preliminary data suggest that antitumor chemotherapy and radiotherapy and celiac plexus block are especially useful modalities of pain control in these patients. The optimal time in the disease course for intervention with celiac plexus block is not known. Further studies are needed to clarify the nature of pain syndromes involved and the role of the various therapeutic modalities.

Pathologic response of the pancreas and duodenum to experimental intraoperative irradiation

The pancreas and duodenum of 24 beagle dogs were given intraoperative irradiation (IORT) with 6 MeV electrons. The dose range was 17.5 Gy to 40 Gy. Billroth II gastrojejunostomy was performed on all dogs prior to irradiation. Six control dogs received only Billroth II surgery. Starting 2 weeks after surgery, dogs in the irradiation groups were given 50 Gy 6 MV X rays external beam radiation therapy (EBRT) to the pancreas and duodenum. The total dose of 50 Gy was given in 2 Gy fractions over 5 weeks. Dogs were monitored for 135 days then necropsied. Gross and histopathologic changes in the pancreas and duodenum were evaluated and quantitative analysis of pancreatic lesions done. Duodenal ulcers were found following 32.5 Gy and 40 Gy IORT. The pancreases were atrophic in irradiated dogs and exocrine pancreatic insufficiency occurred in one dog given 25 Gy. Gross pancreatic atrophy correlated with IORT dose. Histopathologic evidence of radiation damage to the pancreas was observed in acinar cells. Islet cell lesions were not apparent. There was pancreatic fibrosis and damage to blood vessels and ducts. Dose-response relationships were observed for the index of damage to the pancreas as a whole, for pancreatic fibrosis and a decrease in normal acinar cells. Although 25 Gy IORT plus 50 Gy EBRT was tolerated by the duodenum to 135 days, these doses may cause later pancreatic injury as an expression of damage to blood vessels and ducts. Exocrine pancreatic insufficiency and diabetes mellitus may thus represent potential late complications of IORT following 25 Gy or higher doses.

Intraoperative irradiation in a rat model: histopathological changes in irradiated segments of duodenum

During intraoperative radiation therapy for carcinoma of the head of the pancreas in humans, a portion of duodenum is often at risk for radiation-induced complications because of its fixed anatomical position within the treatment field. This study was undertaken to determine the feasibility of using the rat as a model to determine the radiotolerance of normal mammalian duodenum. The procedures used to exteriorize and irradiate a selected segment of duodenum are described. Histopathologic changes in 5-cm segments of midduodenum were studied 14 and 28 days after 0, 30, 40, or 50 Gy X-radiation. Complete denudation of the epithelium and thickening of the muscularis and serosal layers occurred in all irradiated segments by day 14. By day 28, even though crypt and villus architectures were atypical, large areas of epithelial regeneration were seen in rats receiving 30 Gy. In contrast, complete denudation of the epithelium were still evident along most of the length of the irradiated segments in rats receiving 40 or 50 Gy. Serosal fibrosis was prominent in all irradiated animals, regardless of dose. These results indicate that radiation doses above 30 Gy carry high risks of complications. The rat is considered a suitable animal model.

Intraoperative radiotherapy for patients with carcinoma of the pancreas. The Howard University Hospital experience, 1978-1986

During the period from 1978 to 1986, 106 patients were diagnosed with carcinoma of the pancreas; 30 of these patients were excluded from this study. Of the remaining 76 patients, 40 did not receive intraoperative radiotherapy (IORT) and were used as the nonrandomized control group for the 36 patients who did receive IORT after histologic confirmation of carcinoma of the pancreas. The records of 35 patients were available for review. The group receiving IORT ranged in ages from 43 to 89 years (20 males and 15 females). Seventeen patients had distant metastatic disease. The primary was located in the head of the pancreas in 32 and the body in three. No patient in this group had a curative resection. All patients were treated by a combination of biliary and gastric bypass prior to or concurrent with IORT. IORT was begun only after obtaining a histologic diagnosis and prior to the completion of any anastomosis. Necrotizing pancreatitis occurred in the treated group. There was no statistically significant difference in the survival of the nonrandomized control and treated groups.

External beam versus intraoperative and external beam irradiation for locally advanced pancreatic cancer

One hundred fifty-nine patients with unresectable but localized pancreatic cancer, as defined at exploratory laparotomy, were treated at the Mayo Clinic between February 1974 to April 1985. Postoperative therapy consisted of 4000 to 6000 cGy external beam irradiation (XRT) alone in 122 patients or 4500 to 5500 cGy XRT in combination with an intraoperative electron boost in 37. In addition, 132 (both groups) received 5-fluorouracil (5-FU) chemotherapy. Local control (LC) at 1 year was 82% with XRT + intraoperative radiation therapy (IORT) versus 48% with XRT and 66% versus 20% at 2 years respectively (P less than 0.0005). Due to the high incidence of hematogenous and/or peritoneal spread in both groups (abdominal failure in 54 and 56% of patients at risk), the decreased frequency of local progression did not translate into an improved survival. Neither median nor long-term survival of the two treatment groups (XRT versus XRT + IORT) was statistically different (median 12.6 months versus 13.4 months, P = 0.25). With tumor arising in the head of the pancreas, survival at 2 years was 18% as opposed to 0% for other locations (P less than 0.01). On the basis of a Cox multivariate analysis, no other treatment or prognostic factor significantly altered survival. Until the problem with systemic failure (usually abdominal) can be resolved, the median and long-term survival of patients with pancreatic carcinoma is likely to remain unchanged. Since IORT appears to improve local control, we will continue to utilize IORT in phase 1, 2 studies which also attempt to decrease the incidence of abdominal failures. Even with IORT + XRT combinations, the incidence of local progression is excessive and radiation dose modifiers need to be evaluated.

History, preliminary results, complications, and future prospects of intraoperative radiotherapy

Intraoperative electron beam radiotherapy (IORT) is a new combined modality therapy in the treatment of cancer. IORT is delivered during a surgical procedure to a tumor or tumor bed and areas of possible local regional spread, with the ability to shield or physically move normal tissues and organs out of the treatment volume. IORT is feasible for various intraabdominal, retroperitoneal, pelvic, and other malignancies. It is possible to increase the total radiation dose, thereby improving the therapeutic ratio; a better local control without an increasing morbidity. Although the optimum use of IORT is still unknown, it is believed that its greatest value is in combination with maximal surgical resection of the tumor with or without external beam radiotherapy (EBRT). IORT is still an experimental treatment modality combining surgery, EBRT, and if necessary, chemotherapy. Because IORT is an expensive treatment method, it is important to determine which method is the best and most convenient for the patient. The answer can be given only when prospective, randomized clinical IORT trials and cost-effectiveness studies are initiated.

Intraoperative irradiation of the canine abdominal aorta and vena cava

The canine abdominal aorta and vena cava were examined 6 months after single doses of intraoperatively delivered electrons (IORT), fractionated external beam X rays, or a combination. The predominant pathologic change in aortas given fractionated doses was a segmental thickening of the subendothelial region of the tunica intima which was due to fibroelastic proliferation. In severe cases, the intimal proliferation caused significant narrowing of the aortic lumen. The greatest proliferation and lumen narrowing resulted from 80 Gy given in 30 fractions, whereas 60 Gy produced little response. In contrast, IORT alone or combined with fractionated doses resulted in mild subendothelial intimal proliferation at all doses. In some aortas there was focal aortic wall thinning after IORT alone or combined with fractionated doses. This response may be explained by increased intimal cell death and lost or delayed proliferative capability caused by large single doses. These studies suggest that large single doses produce structural alterations in the walls of large blood vessels that are clinically undetectable at early post-irradiation times. If these changes progress in severity they could lead to late effects such as rupture, fissure, or aneurysm that are clinically more significant than the marked intimal proliferation and lumen narrowing changes seen after fractionated doses. The aortic cell responsible for intimal fibroelastic proliferation appears to be a pluripotential stem cell capable of producing fibrous, elastic, and possibly smooth muscle tissue. There were no significant alterations in any of the irradiated vena cavas.

Intraoperative and external beam irradiation +/- 5-FU for locally advanced pancreatic cancer

Because of the poor local control rates obtained with external beam irradiation +/- chemotherapy for locally advanced pancreatic cancer, our institution has used intraoperative radiation therapy (IORT) with electrons to deliver a single "boost" dose of radiation in 52 patients with biopsy-proven adenocarcinoma (primary, unresectable-49; primary, residual-2; and recurrent, unresectable-1). Patients received 4500-5000 rad of fractionated external beam irradiation and an IORT dose of 1750 rad (2 patients) or 2000 rad (50 patients). Acute and chronic tolerance have been acceptable. Documented local progression within either the external beam or IORT fields has been infrequent (3 of 42 evaluable patients or 7%), but there has been little, if any, change in median or long-term survival from that seen in external beam series. This is probably because of a high incidence of liver and peritoneal metastases with pancreatic cancer. A phase II pilot trial, which combines upper or total abdominal irradiation and infusion 5-FU with tumor nodal irradiation plus IORT, is in progress in our institution to evaluate tolerance and the relative incidence of abdominal failures.

Tolerance of canine portal vein anastomosis to intraoperative x-irradiation

Tolerance of surgical portal vein anastomosis to intraoperative radiation therapy (IORT) was studied in dogs after single doses of zero, 10, 20 and 40 Gy (290 kVp x-rays). Portal venography was performed prior to IORT and before sacrificing. The dogs were sacrificed 3 and 12 months respectively after irradiation. Portal venography revealed no radiation induced anastomotic stenosis. Autopsy disclosed macroscopic periportal fibrosis in all dogs, independent of radiation dose and observation periods. Microscopically, the three tunicas of the vein did not show any pathological changes after any dose level.

Quality control parameters of intraoperative radiation therapy

We have tried to outline many of the factors which must be considered in the technical delivery of IORT and in subsequent evaluation of these patients. Unless careful attention is given to details of patient selection, surgery, pathology, radiation therapy and follow-up, it is likely that a vast morass of data will be obtained which will be very difficult to interpret. It is the hope of the IORT Working Group that other institutions using IORT will employ our recommendations with regard to dosimetry, follow-up, and the general technical approach. This will likely lead to an earlier understanding of the exact role of this modality in cancer therapy today.

Intraoperative radiotherapy

The potential benefit of intraoperative radiotherapy (IORT) was originally recognized years ago and has recently attracted renewed interest. Modern radiotherapeutic approaches may be more successful as a result of technical innovation, particularly in the use of electron beam accelerators. Preliminary studies, mainly uncontrolled and nonrandomized, have assessed the role of IORT for treatment of a variety of deep seated abdominal, retroperitoneal, and pelvic cancers. The results of some studies show much promise, but prospective trials are needed to scientifically validate these favorable initial observations.

Residual, recurrent, or unresectable gastrointestinal cancer. Role of radiation in single or combined modality treatment

When conventional modalities of external beam irradiation and chemotherapy +/- resection are used in the treatment of locally advanced gastrointestinal malignancies, although useful palliation can be achieved in many patients, cure and long-term survival is infrequent. Aggressive combined modality approaches have recently encorporated irradiation boost techniques with intraoperative electrons or intraoperative or transcatheter brachytherapy. Both local control and long-term survival appear to be improved when compared with results achieved with conventional treatment. Randomized trials are needed to determine if the observed differences are real or due to differences in case selection.

Orthovoltage intraoperative radiotherapy: a new look at an old idea

A 300 kvp orthovoltage machine has been permanently installed in an operating room for delivering intraoperative radiation therapy (IORT). A historical review of orthovoltage IORT and our present approach are described. The preliminary experience with 38 patients treated with orthovoltage IORT indicates that this technique is feasible, has low acute morbidity, and can be useful for palliation. "Radical" radiation therapy consisting of IORT "boost" treatment combined with external beam was used in 24 patients with primary or recurrent cancer. Local failure in 27 patients treated with IORT +/- external beam radiation therapy was 56%, but varied from 11% (1/9) for patients with resected disease to 78% (14/18) for patients with unresected disease. Complications occurred in nine patients (24%) and have been acceptable. There are 17 patients alive and six are NED, with follow-up of 4-18 months. There appears to be a role for orthovoltage IORT especially when combined with surgical resection for local control of advanced cancer arising in the abdomen where the use of high doses of external radiation therapy are hazardous.

Intraoperative electron beam irradiation for patients with unresectable pancreatic carcinoma

Since 1978 we have used electron beam intraoperative radiation therapy (IORT) to deliver higher radiation doses to pancreatic tumors than are possible with external beam techniques while minimizing the dose to the surrounding normal tissues. Twenty-nine patients with localized, unresectable, pancreatic carcinoma were treated by electron beam IORT in combination with conventional external radiation therapy (XRT). The primary tumor was located in the head of the pancreas in 20 patients, in the head and body in six patients, and in the body and tail in three. Adjuvant chemotherapy was given in 23 of the 29 patients. The last 13 patients have received misonidazole (3.5 mg/M2) just prior to IORT (20 Gy). At present 14 patients are alive and 11 are without evidence of disease from 3 to 41 months after IORT. The median survival is 16.5 months. Eight patients have failed locally in the IORT field and two others failed regionally. Twelve patients have developed distant metastases, including five who failed locally or regionally. We have seen no local recurrences in the 12 patients who have been treated with misonidazole and have completed IORT and XRT while 10 of 15 patients treated without misonidazole have recurred locally. Because of the shorter follow-up in the misonidazole group, this apparent improvement is not statistically significant. Fifteen patients (52%) have not had pain following treatment and 22 (76%) have had no upper gastrointestinal or biliary obstruction subsequent to their initial surgical bypasses and radiation treatments. Based on the good palliation generally obtained, the 16.5-month median survival, and the possible added benefit from misonidazole, we are encouraged to continue this approach.

Tolerance of canine anastomoses to intraoperative radiation therapy

Radiation has been given intraoperatively to various abdominal structures in dogs, using a fixed horizontal 11 MeV electron beam at the Armed Forces Radiobiologic Research Institute. Animals were irradiated with single doses of 2000, 3000 and 4500 rad to a field which extended from the bifurcation of the aorta to the rib cage. All animals were irradiated during laparotomy under general anesthesia. Because the clinical use of intraoperative radiotherapy in cancer treatment will occasionally require irradiation of anastomosed large vessels and blind loops of bowel, the tolerance of aortic anastomoses and the suture lines of blind loops of jejunum to irradiation were studied. Responses in these experiments were scored at times up to one year after irradiation. In separate experiments both aortic and intestinal anastomoses were performed on each animal for evaluation of short term response. Response was graded by arteriography, gastrointestinal roentgenography, blind loop bursting pressure, and pathologic findings at autopsy and microscopic evaluation. The dogs with aortic anastomoses showed adequate healing at all doses with no evidence of suture line weakening. On long-term follow-up one animal (2000 rad) had stenosis at the anastomosis and one animal (4500 rad) developed an arteriovenous fistula. Three of the animals that had an intestinal blind loop irradiated subsequently developed intussusception, with the irradiated loop acting as the lead point. One week after irradiation, bursting pressure of an intestinal blind loop was normal at 3000 rad, but markedly decreased at 4500 rad. No late complications were noted after the irradiation of the intestinal anastomosis. Thus, it appears that adequate healing can take place with minimal risk of suture line breakdown even after a high single dose of irradiation (up to 3000 rad) to an anastomotic site. No late complications were observed after irradiation of intestinal anastomoses, but one needs to be cautious with regards to possible late stenosis at the site of an irradiated vascular anastomosis.

Progress in cancer management. Keynote address

Management of cancer has changed drastically since the end of World War II. From the turn of the century up to that time, surgery had been the bulwark against cancer. Now in addition, over 2000 medical oncologists and over 1000 radiologists play a large role in cancer management. The majority of these were trained within the past decade through resources provided by the National Cancer Act. Early radiotherapeutic equipment caused such toxicity that scientific articles in the 1920s and 1930s questioned the utility of radiotherapy, just as they would chemotherapy at a later date. Improvement in cancer cure rates due to surgery, modern anesthesia, blood transfusions and antibiotics for serious cancers, had plateaued at about 30%. Since the introduction of the first cobalt units and then linear accelerators into medical practice in the mid-1950s, an additional 90,000 patients a year are curable by the use of radiotherapy alone, or in combination with surgery (1980 data). The first chemotherapy was introduced in about 1950, but effective treatment with drugs in the clinic really began in the 1960s. By 1970, some 11,000 patients were curable by drugs alone. Now, with the capability for combining all three therapies, chemotherapy alone, or in conjunction with radiotherapy and surgery, is responsible for the eradication of cancer in some 46,000 patients a year. There are two prime therapeutic targets for the 1980s: First, those approximately 100,000 patients treated with radiotherapy for cure who subsequently develop local recurrences; and second, the approximately 200,000 patients who, when operated on or treated with radiotherapy for localized tumors, still develop recurrent cancers at sites distal to the primary due to micrometastases. Prospects for controlling both types of treatment failures are bright and will be reviewed.