Low dose fractionated whole body irradiation in the treatment of advanced non-Hodgkin's lymphoma

Hematological Changes Following Low Dose Radiation Therapy and Comparison to Current Standard of Care Cancer Treatments

Cancer is the second leading cause of mortality worldwide accounting for almost 10 million deaths in 2020. Current standard of care treatment varies depending on the type and stage of disease, but commonly includes surgery, chemotherapy, and/or radiation therapy. There is evidence that whole- and half-body exposure to low dose ionizing radiation can also be an effective therapeutic due to its stimulation of anti-cancer immunity. One of the limiting factors for past clinical trials using low dose radiation therapy has been adverse hematological events. However, similar hematological changes are also frequently reported following standard of care treatments in oncology. This review summarizes the effects of various cancer therapies on hematologic toxicity through the evaluation of complete blood count reports. The reviewed literature elucidates hematological trends in patients undergoing chemotherapy, and both high and low dose radiation therapy. In general, high dose radiation and chemotherapy can result in widespread changes in blood counts, with the most severe effects related to leukopenia. Overall, compared to standard of care treatments, low dose radiation results in similar, yet more mild hematological changes. Taken together, hematological toxicities should not be a limiting factor in the applicability of low dose radiation as a cancer therapeutic.

Radiophobia Overreaction: College of Chiropractors of British Columbia Revoke Full X-Ray Rights Based on Flawed Study and Radiation Fear-Mongering

Fears over radiation have created irrational pressures to dissuade radiography use within chiropractic. Recently, the regulatory body for chiropractors practicing in British Columbia, Canada, the College of Chiropractors of British Columbia (CCBC), contracted Pierre Côté to review the clinical use of X-rays within the chiropractic profession. A "rapid review" was performed and published quickly and included only 9 papers, the most recent dating from 2005; they concluded, "Given the inherent risks of radiation, we recommend that chiropractors do not use radiographs for the routine and repeat evaluation of the structure and function of the spine." The CCBC then launched an immediate review of the use of X-rays by chiropractors in their jurisdiction. Member and public opinion were gathered but not presented to their members. On February 4, 2021, the College announced amendments to their Professional Conduct Handbook that revoked X-ray rights for routine/repeat assessment and management of patients with spine disorders. Here, we highlight current and historical evidence that substantiates that X-rays are not a public health threat. We also point out critical and insurmountable flaws in the single paper used to support irrational and unscientific policy that discriminates against chiropractors who practice certain forms of evidence-based X-ray-guided methods.

Time to rejuvenate ultra-low dose whole-body radiotherapy of cancer

The results of clinical trials performed from the 1930s until the end of the 20th century in which total-body ultra-low level ionizing radiation (TB-LLR) was used demonstrate that this form of treatment can be equal or superior to other systemic anti-neoplastic modalities in terms of the rates of remissions, toxicity, and side effects. In this review, we provide the rationale for TB-LLR and analyze the results of reliable clinical trials in patients with predominantly lymphoproliferative disorders but also advanced solid cancers. The doses used in these trials did not exceed 0.1-0.2 Gy per fraction and cumulative totals ranged from 1 to 4 Gy. Based on the reviewed results we conclude that it is appropriate to revive interest in and resume clinical investigations of TB-LLR in order to refine and improve the effectiveness of such treatment, whether employed alone or in combination with other anticancer strategies.

Radiophobic Fear-Mongering, Misappropriation of Medical References and Dismissing Relevant Data Forms the False Stance for Advocating Against the Use of Routine and Repeat Radiography in Chiropractic and Manual Therapy

There is a faction within the chiropractic profession passionately advocating against the routine use of X-rays in the diagnosis, treatment and management of patients with spinal disorders (aka subluxation). These activists reiterate common false statements such as "there is no evidence" for biomechanical spine assessment by X-ray, "there are no guidelines" supporting routine imaging, and also promulgate the reiterating narrative that "X-rays are dangerous." These arguments come in the form of recycled allopathic "red flag only" medical guidelines for spine care, opinion pieces and consensus statements. Herein, we review these common arguments and present compelling data refuting such claims. It quickly becomes evident that these statements are false. They are based on cherry-picked medical references and, most importantly, expansive evidence against this narrative continues to be ignored. Factually, there is considerable evidential support for routine use of radiological imaging in chiropractic and manual therapies for 3 main purposes: 1. To assess spinopelvic biomechanical parameters; 2. To screen for relative and absolute contraindications; 3. To reassess a patient's progress from some forms of spine altering treatments. Finally, and most importantly, we summarize why the long-held notion of carcinogenicity from X-rays is not a valid argument.

5 Reasons Why Scoliosis X-Rays Are Not Harmful

Radiographic imaging for scoliosis screening, diagnosis, treatment, and management is the gold standard assessment tool. Scoliosis patients receive many repeat radiographs, typically 10-25 and as many as 40-50, equating to a maximum 50 mGy of cumulative exposure. It is argued this amount of radiation exposure is not carcinogenic to scoliosis patients for 5 main reasons: 1. Estimated theoretical cumulative effective doses remain below the carcinogenic dose threshold; 2. Scoliosis patient x-rays are delivered in serial exposures and therefore, mitigate any potential cumulative effect; 3. Linear no-threshold cancer risk estimates from scoliosis patient cohorts are flawed due to faulty science; 4. Standardized incidence/mortality ratios demonstrating increased cancers from aged scoliosis cohorts are confounded by the effects of the disease entity itself making it impossible to claim cause and effect resulting from low-dose radiation exposures from spinal imaging; 5. Children are not more susceptible to radiation damage than adults. Radiophobia concerns from patients, parents, and doctors over repeat imaging for scoliosis treatment and management is not justified; it adds unnecessary anxiety to the patient (and their parents) and interferes with optimal medical management. X-rays taken in the evidence-based management of scoliosis should be taken without hesitation or concern about negligible radiation exposures.

Are Restrictive Medical Radiation Imaging Campaigns Misguided? It Seems So: A Case Example of the American Chiropractic Association's Adoption of "Choosing Wisely"

Since the 1980s, increased utilization of medical radiology, primarily computed tomography, has doubled medically sourced radiation exposures. Ensuing fear-mongering media headlines of iatrogenic cancers from these essential medical diagnostic tools has led the public and medical professionals alike to display escalating radiophobia. Problematically, several campaigns including Image Gently, Image Wisely, and facets of Choosing Wisely propagate fears of all medical radiation, which is necessary for the delivery of effective and efficient health care. Since there are no sound data supporting the alleged risks from low-dose radiation and since there is abundant evidence of health benefits from low-doses, these imaging campaigns seem misguided. Further, thresholds for cancer are 100 to 1000-fold greater than X-rays, which are within the realm of natural background radiation where no harm has ever been validated. Here, we focus on radiographic imaging for use in spinal rehabilitation by manual therapists, chiropractors, and physiotherapists as spinal X-rays represent the lowest levels of radiation imaging and are critical in the diagnosis and management of spine-related disorders. Using a case example of a chiropractic association adopting "Choosing Wisely," we argue that these campaigns only fuel the pervasive radiophobia and continue to constrain medical professionals, attempting to deliver quality care to patients.

Death of the ALARA Radiation Protection Principle as Used in the Medical Sector

ALARA is the acronym for "As Low As Reasonably Achievable." It is a radiation protection concept borne from the linear no-threshold (LNT) hypothesis. There are no valid data today supporting the use of LNT in the low-dose range, so dose as a surrogate for risk in radiological imaging is not appropriate, and therefore, the use of the ALARA concept is obsolete. Continued use of an outdated and erroneous principle unnecessarily constrains medical professionals attempting to deliver high-quality care to patients by leading to a reluctance by doctors to order images, a resistance from patients/parents to receive images, subquality images, repeated imaging, increased radiation exposures, the stifling of low-dose radiation research and treatment, and the propagation of radiophobia and continued endorsement of ALARA by regulatory bodies. All these factors result from the fear of radiogenic cancer, many years in the future, that will not occur. It has been established that the dose threshold for leukemia is higher than previously thought. A low-dose radiation exposure from medical imaging will likely upregulate the body's adaptive protection systems leading to the prevention of future cancers. The ALARA principle, as used as a radiation protection principle throughout medicine, is scientifically defunct and should be abandoned.

Health Impacts of Low-Dose Ionizing Radiation: Current Scientific Debates and Regulatory Issues

Health impacts of low-dose ionizing radiation are significant in important fields such as X-ray imaging, radiation therapy, nuclear power, and others. However, all existing and potential applications are currently challenged by public concerns and regulatory restrictions. We aimed to assess the validity of the linear no-threshold (LNT) model of radiation damage, which is the basis of current regulation, and to assess the justification for this regulation. We have conducted an extensive search in PubMed. Special attention has been given to papers cited in comprehensive reviews of the United States (2006) and French (2005) Academies of Sciences and in the United Nations Scientific Committee on Atomic Radiation 2016 report. Epidemiological data provide essentially no evidence for detrimental health effects below 100 mSv, and several studies suggest beneficial (hormetic) effects. Equally significant, many studies with in vitro and in animal models demonstrate that several mechanisms initiated by low-dose radiation have beneficial effects. Overall, although probably not yet proven to be untrue, LNT has certainly not been proven to be true. At this point, taking into account the high price tag (in both economic and human terms) borne by the LNT-inspired regulation, there is little doubt that the present regulatory burden should be reduced.

Cancer immunotherapy: how low-level ionizing radiation can play a key role

The cancer immunoediting hypothesis assumes that the immune system guards the host against the incipient cancer, but also "edits" the immunogenicity of surviving neoplastic cells and supports remodeling of tumor microenvironment towards an immunosuppressive and pro-neoplastic state. Local irradiation of tumors during standard radiotherapy, by killing neoplastic cells and generating inflammation, stimulates anti-cancer immunity and/or partially reverses cancer-promoting immunosuppression. These effects are induced by moderate (0.1-2.0 Gy) or high (>2 Gy) doses of ionizing radiation which can also harm normal tissues, impede immune functions, and increase the risk of secondary neoplasms. In contrast, such complications do not occur with exposures to low doses (≤0.1 Gy for acute irradiation or ≤0.1 mGy/min dose rate for chronic exposures) of low-LET ionizing radiation. Furthermore, considerable evidence indicates that such low-level radiation (LLR) exposures retard the development of neoplasms in humans and experimental animals. Here, we review immunosuppressive mechanisms induced by growing tumors as well as immunomodulatory effects of LLR evidently or likely associated with cancer-inhibiting outcomes of such exposures. We also offer suggestions how LLR may restore and/or stimulate effective anti-tumor immunity during the more advanced stages of carcinogenesis. We postulate that, based on epidemiological and experimental data amassed over the last few decades, whole- or half-body irradiations with LLR should be systematically examined for its potential to be a viable immunotherapeutic treatment option for patients with systemic cancer.

Potential treatment of inflammatory and proliferative diseases by ultra-low doses of ionizing radiations

Ultra-low doses and dose- rates of ionizing radiation are effective in preventing disease which suggests that they also may be effective in treating disease. Limited experimental and anecdotal evidence indicates that low radiation doses from radon in mines and spas, thorium-bearing monazite sands and enhanced radioactive uranium ore obtained from a natural geological reactor may be useful in treating many inflammatory conditions and proliferative disorders, including cancer. Optimal therapeutic applications were identified via a literature survey as dose-rates ranging from 7 to 11μGy/hr or 28 to 44 times world average background rates. Rocks from an abandoned uranium mine in Utah were considered for therapeutic application and were examined by γ-ray and laser-induced breakdown fluorescence spectroscopy. The rocks showed the presence of transuranics and fission products with a γ-ray energy profile similar to aged spent uranium nuclear fuel (93% dose due to β particles and 7% due to γ rays). Mud packs of pulverized uranium ore rock dust in sealed plastic bags delivering bag surface β,γ dose-rates of 10-450 μGy/h were used with apparent success to treat several inflammatory and proliferative conditions in humans.

Low-dose radiation therapy of cancer: role of immune enhancement

The efficacy of conventional radiation therapy, one of the most widely used treatment modalities of cancer, is limited by resistance of tumors as well as normal tissue toxicity. In the last decade, several studies have shown that protocols using low-dose radiation (LDR) are more effective in providing local tumor control with negligible normal tissue toxicity. LDR stimulates antioxidant capacity, repair of DNA damage, apoptosis and induction of immune responses, which might be collectively responsible for providing effective local tumor control. This article focuses on the immunostimulatory effects of LDR in in vivo models and its clinical efficacy, supporting the use of LDR regimens (alone or as adjuvant) as an anticancer treatment.

Immunological mechanism of the low-dose radiation-induced suppression of cancer metastases in a mouse model

According to the doctrine underlying the current radiation protection regulations each, no matter how small, exposure to ionizing radiation may be carcinogenic. However, numerous epidemiological observations demonstrate that cancer incidence and/or mortality are not elevated among inhabitants of the high- versus low-natural-background radiation areas and homes. Results of our own and other authors' studies described in this paper bear testimony to the possibility that stimulation of the anti-neoplastic immune surveillance mediated by NK lymphocytes and activated macrophages explains, at least partially, the accumulating epidemiological and experimental evidence indicating that low-level exposures to the low-linear energy transfer (LET) radiation inhibit the development of spontaneous and artificial metastases in humans and laboratory animals, respectively. The results presented also suggest the possibility of using low-level X- and gamma-ray exposures to cure cancer and to prevent cancer metastases. For a broader perspective, the results presented may help towards relaxing the current radiation protection regulations, especially as they apply to diagnostic and therapeutic exposures of patients to the indicated forms of radiation.

Nuclear energy and health: and the benefits of low-dose radiation hormesis

Energy needs worldwide are expected to increase for the foreseeable future, but fuel supplies are limited. Nuclear reactors could supply much of the energy demand in a safe, sustainable manner were it not for fear of potential releases of radioactivity. Such releases would likely deliver a low dose or dose rate of radiation, within the range of naturally occurring radiation, to which life is already accustomed. The key areas of concern are discussed. Studies of actual health effects, especially thyroid cancers, following exposures are assessed. Radiation hormesis is explained, pointing out that beneficial effects are expected following a low dose or dose rate because protective responses against stresses are stimulated. The notions that no amount of radiation is small enough to be harmless and that a nuclear accident could kill hundreds of thousands are challenged in light of experience: more than a century with radiation and six decades with reactors. If nuclear energy is to play a significant role in meeting future needs, regulatory authorities must examine the scientific evidence and communicate the real health effects of nuclear radiation. Negative images and implications of health risks derived by unscientific extrapolations of harmful effects of high doses must be dispelled.

Low-dose radioimmuno-therapy of cancer

Four decades of genomic, cellular, animal and human data have shown that low-dose ionizing radiation stimulates positive genomic and cellular responses associated with effective cancer prevention and therapy and increased life span of mammals and humans.( 1-8) Nevertheless, this data is questioned because it seems to contradict the well demonstrated linear relation between ionizing radiation dose and damage to DNA without providing a clear mechanistic explanation of how low-dose radiation could produce such beneficial effects. This apparent contradiction is dispelled by current radiobiology that now includes DNA damage both from ionizing radiation and from endogenous metabolic free radicals, and coupled with the biological response to low-dose radiation. Acceptance of current radiobiology would invalidate long established recommendations and regulations of worldwide radiation safety organizations and so destroy the basis of the very expensive existing system of regulation and remediation. More importantly, current radiobiology would facilitate urgently needed clinical trials of low dose radiation (LDR) cancer therapy.

Sparsely ionizing diagnostic and natural background radiations are likely preventing cancer and other genomic-instability-associated diseases

Routine diagnostic X-rays (e.g., chest X-rays, mammograms, computed tomography scans) and routine diagnostic nuclear medicine procedures using sparsely ionizing radiation forms (e.g., beta and gamma radiations) stimulate the removal of precancerous neo-plastically transformed and other genomically unstable cells from the body (medical radiation hormesis). The indicated radiation hormesis arises because radiation doses above an individual-specific stochastic threshold activate a system of cooperative protective processes that include high-fidelity DNA repair/apoptosis (presumed p53 related), an auxiliary apoptosis process (PAM process) that is presumed p53-independent, and stimulated immunity. These forms of induced protection are called adapted protection because they are associated with the radiation adaptive response. Diagnostic X-ray sources, other sources of sparsely ionizing radiation used in nuclear medicine diagnostic procedures, as well as radioisotope-labeled immunoglobulins could be used in conjunction with apoptosis-sensitizing agents (e.g., the natural phenolic compound resveratrol) in curing existing cancer via low-dose fractionated or low-dose, low-dose-rate therapy (therapeutic radiation hormesis). Evidence is provided to support the existence of both therapeutic (curing existing cancer) and medical (cancer prevention) radiation hormesis. Evidence is also provided demonstrating that exposure to environmental sparsely ionizing radiations, such as gamma rays, protect from cancer occurrence and the occurrence of other diseases via inducing adapted protection (environmental radiation hormesis).

Radiobiological basis of low-dose irradiation in prevention and therapy of cancer

Antimutagenic DNA damage-control is the central component of the homeostatic control essential for survival. Over eons of time, this complex DNA damage-control system evolved to control the vast number of DNA alterations produced by reactive oxygen species (ROS), generated principally by leakage of free radicals from mitochondrial metabolism of oxygen. Aging, mortality and cancer mortality are generally accepted to be associated with stem cell accumulation of permanent alterations of DNA, i.e., the accumulation of mutations. In a young adult, living in a low LET background of 0.1 cGy/y, the antimutagenic system of prevention, repair and removal of DNA alterations reduces about one million DNA alterations/cell/d to about one mutation/cell/d. DNA alterations from background radiation produce about one additional mutation per 10 million cells/d. As mutations accumulate and gradually degrade the antimutagenic system, aging progresses at an increasing rate, mortality increases correspondingly, and cancer increases at about the fourth power of age. During the past three decades, genomic, cellular, animal and human data have shown that low-dose ionizing radiation, including acute doses up to 30 cGy, stimulates each component of the homeostatic antimutagenic control system of antioxidant prevention, enzymatic repair, and immunologic and apoptotic removal of DNA alterations. On the other hand, high-dose ionizing radiation suppresses each of these antimutagenic protective components. Populations living in high background radiation areas and nuclear workers with increased radiation exposure show lower mortality and decreased cancer mortality than the corresponding populations living in low background radiation areas and nuclear workers without increased radiation exposure. Both studies of cancer in animals and clinical trials of patients with cancer also show, with high statistical confidence, the beneficial effects of low-dose radiation.

Antitumor Effects by Low Dose Total Body Irradiation

Total-body irradiation (TBI) with 0.02-0.25 Gy has been reported to have antitumor effects. In mice, low-dose TBI induces tumor growth delay, antimetastatic effects, suppressive effects on the incidence of spontaneous thymiclymphoma, sensitization of tumor to ionizing radiation, and decrease in TD50 value. In artificial metastasis, 0.20 Gy TBI suppressed lung metastasis when it was conducted between 3 h before and 3 h after tumor cell injection into a tail vein. In spontaneous metastasis, 0.15-0.20 Gy TBI suppressed lung metastasis. Irradiation with 0.15 Gy twice a week from 11 weeks of age for 40 weeks significantly suppressed the incidence of spontaneous thymic lymphoma in AKR/J mice, which caused prolonged life span. Low-dose TBI has been used in the clinical treatment of lymphomatous malignancies including chronic lymphocytic leukaemia (CLL) and non-Hodgkin's lymphoma (NHL). The usual practice was to give 0.1 Gy TBI three times a week or 0.15 Gy TBI two times a week to a total dose of 1.5 Gy. Despite this low total dose, low-dose fractionated TBI could induce long-term remissions and was as effective as the chemotherapy to which it was compared. Experimental data suggest that the antitumor effects of low-dose TBI could be explained by immune enhancement, induction of apoptosis, and intrinsic hypersensitivity to low-dose irradiation. Possible mechanisms of immune enhancement are elimination of the T-suppressor subset of lymphocytes and augmentation of the immune response including alteration of cytokine release and enhanced proliferative activity of lymphocytes to mitogenic stimuli.

Radiobiological basis for cancer therapy by total or half-body irradiation

The tumor control effects by total-body irradiation (TBI) or half-body irradiation (HBI) on tumor-bearing mice and human cancer were investigated. In fundamental studies using a murine experimental system, mice that received 10 or 15 cGy of TBI showed a high value of TD(50) (number of tumor cells required for successful transplantation to a half group of injected sites) compared with nonirradiated control mice. The combination of low doses of TBI and local irradiation on tumor-bearing mice demonstrated enhanced tumor cell killing compared with only local irradiation, but this tumor-cell killing effect was not observed following 10 or 15 cGy of TBI alone. However, the suppression of distant metastasis of tumor cells was observed following low doses of TBI alone. Immunological studies on these effects suggested that TBI or HBI caused immunopotentiating effects. In clinical studies, malignant lymphoma (non-Hodgkin's lymphoma) was selected as the first disease for clinical trial. The results were promising for tumor control applications, except for advanced cases and very aged patients.

Phase II study of palliative low-dose local radiotherapy in disseminated indolent non-Hodgkin's lymphoma and chronic lymphocytic leukemia

PURPOSE

Indolent non-Hodgkin's lymphoma (INHL) and chronic lymphocytic leukemia (CLL) are highly sensitive to radiotherapy (RT). Previous retrospective studies have shown high response rates after local palliative RT of 4 Gy in 2 fractions, which prompted this prospective Phase II trial of the palliative effect of this regimen in patients with disseminated INHL or CLL.

METHODS AND MATERIALS

Twenty-two patients (11 men, 11 women, median age 62 years, range 30-89) with disseminated INHL (n = 15) or CLL (n = 7) were treated with local low-dose RT, 2 Gy x 2 within 3 days, with the aim of achieving palliation from localized lymphoma masses. The patients were treated to a total of 31 different sites. Seventeen patients had previously been treated with chemotherapy. The median observation time after the start of RT was 8 months (range 3-26).

RESULTS

All patients and all irradiated sites were assessable for response. Of the 22 patients, 18 responded to the treatment, corresponding to an overall response rate (RR) of 82%; 12 patients (55%) achieved a complete response (CR), 5 patients (22%) a partial response (PR), and 1 patient had a CR at three sites and a PR at one site. Of the 31 irradiated sites, 27 responded to treatment, corresponding to an overall RR of 87%; in 20 sites (65%) a CR was achieved and in 7 sites (22%) a PR. Patients with disseminated INHL had an overall RR of 87% (74% CR, 13% PR); patients with CLL had an overall RR of 71% (29% CR, 42% PR). The median duration of response was estimated at 22 months. None of the patients had significant side effects from the treatment.

CONCLUSION

Low-dose RT (4 Gy in 2 fractions) is a highly effective palliative treatment of localized lymphoma masses in patients with disseminated INHL and CLL. The treatment has minimal side effects.

Induction of interleukin-1beta and interleukin-6 mRNA by low doses of ionizing radiation in macrophages

We have previously reported the antimetastatic effects and augmentation of immune responses, which would be a mechanism of the antimetastatic effects, of 0.1 to 0.2 Gy total body irradiation. To elucidate the cellular mechanisms of the augmentation of immune response, we investigated the effects of low-dose irradiation on gene expression of interleukin-1beta (IL-1beta) and IL-6 using mouse peritoneal macrophages in vitro. Absolute mRNA quantification was carried out using competitive polymerase chain reaction. Gene expression of IL-1beta and IL-6 was increased 1 to 2 hr after 2.0 Gy irradiation and then decreased to below the basal expression level 4 hr after irradiation. Irradiation with 0.1 Gy increased IL-6 expression 2 hr after irradiation, but it did not affect IL-1beta expression. Downregulation of IL-1beta and IL-6 observed 4 hr after 2.0 Gy irradiation was not observed with 0.1 Gy irradiation. The protein kinase C (PKC) inhibitor H7 and the phosphatidylinositol 3-kinase (PI3-kinase) inhibitor wortmannin inhibited induction of IL-1beta and IL-6 expression, which suggests that radiation-induced IL-1beta and IL-6 expression is achieved by PKC- and PI3-kinase-mediated signaling.

A high and sustained response rate in refractory or relapsing low-grade lymphoma masses after low-dose radiation: analysis of predictive parameters of response to treatment

PURPOSE

To determine the efficacy of small doses of radiation in patients with recurrent or refractory low-grade lymphoma masses.

METHODS AND MATERIALS

Patients with refractory or relapsing low-grade lymphoma masses. The two largest diameters of the tumor mass were measured, whenever possible, before and after treatment. A dose of 4 Gy of radiotherapy was delivered to tumor sites in 2 fractions. Patients were evaluated for response 1-4 months later and at regular follow-up visits.

RESULTS

Forty-eight patients with low-grade lymphomas according to the working formulation received low-dose radiotherapy between March 1987 and November 1998. Most patients had advanced disease at the time of radiation treatment, and 80% had received at least two chemotherapy regimens before treatment. The median interval between the initial diagnosis and radiotherapy was 2.7 years (range 0-22 years). Low-dose radiation was delivered to 135 tumor sites. Nodal and extranodal tumor sites represented 80% and 20% of masses, respectively. An objective response was obtained in 81% of the sites, with 57% attaining a complete remission. The 2-year actuarial freedom from local progression (FFLP) rate was 56% (95% CI, 46-66%). Tumor masses </=5 cm in diameter had a significantly higher 2-year FFLP rate than larger masses (51% vs. 27%). It is noteworthy that the 2-year FFLP rate for patients treated with less than 2 chemotherapy regimens before radiotherapy was significantly higher than the 2-year FFLP rate for more heavily treated patients (96% vs. 48%). The 2-year FFLP rates for extranodal tumor sites and nodal sites were not significantly different. The tumor size (< or =5 cm vs. > 5 cm), the number of chemotherapy regimens (0-1 vs. more), and age at time of radiation treatment (< or =65 years or > 65 years) were significant predictive parameters of response to treatment.

CONCLUSIONS

In this retrospective study, low-dose radiation proved efficient, with long-lasting effects in the majority of patients with recurrent or refractory low-grade lymphomas. This simple and nontoxic treatment should be investigated prospectively in patients with advanced disease and a low tumor burden not immediately warranting chemotherapy.

The immunobiology of low-dose total-body irradiation: more questions than answers

Low-dose total-body irradiation (TBI) is used in the treatment of chronic lymphocytic leukemia and low-grade non-Hodgkin's lymphoma. The usual practice is to give very low individual fractions (0.1 to 0.25 Gy) several times a week, to a total dose of 1.5 to 2 Gy. Despite this low dose, low-dose TBI can induce long-term remissions in the majority of patients. Immune enhancement, rather than direct radiation cell killing, is one of the suggested mechanisms by which low-dose TBI can exert its effect. Data from animal experiments have shown that low-dose TBI could enhance the immune response through (1) augmenting the proliferative reactive response of the T cells to mitogenic stimulation; (2) altering cytokine release, particularly the activation of interferon gamma and Il2 production; (3) increasing the expression of Il2 receptors on the T-cell surface; (4) facilitating signal transduction in T lymphocytes; (5) increasing splenic catecholamine content and lowering the serum corticosterone level; and (6) eliminating a particularly radiosensitive subset of the suppressor T cells. Data for humans, though scarce, suggest that at least some of these mechanisms occur in patients treated with low-dose TBI. Whether these immunomodulatory effects are responsible for the clinical outcome is not yet clear. Much is still unknown about the immunobiology of low-dose TBI, its clinical potential, and the possible synergism with chemotherapy, biological response modifiers, or immunotherapy. This lack of comprehensive knowledge hampers the optimal and widespread use of this intriguing and potentially useful treatment modality in clinical practice.

In vitro radiation-induced apoptosis and early response to low-dose radiotherapy in non-Hodgkin's lymphomas

PURPOSE

Prospective investigation of spontaneous and in vitro radiation-induced apoptosis to predict early response to palliative radiotherapy in patients with non-Hodgkin's lymphomas.

PATIENTS AND METHODS

Fine-needle sampling was performed in 28 tumor sites (26 patients) and yielded adequate cell numbers in 27 cases. Apoptotic cells were counted by fluorescence microscopy immediately after sampling and after 24-h culture (spontaneous apoptosis) and 24 h after 2- and 10-Gy in vitro irradiation (radiation-induced apoptosis). Early response to low-dose in vivo radiotherapy (mostly 4 Gy in two fractions over 3 days) was evaluated 15 days after treatment.

RESULTS

The tumor response rates at 15 days were 11 (39%) complete responses, nine (32%) responses of greater than 50% reduction in volume, six (21%) responses of less than 50% reduction in volume and two (7%) cases of no response. Tumors achieving complete or major response after in vivo irradiation had higher percentages of apoptotic cells after in vitro irradiation, while no significant differences in terms of spontaneous apoptosis were observed between responders and non-responders.

CONCLUSION

Spontaneous and in vitro radiation-induced apoptosis can be easily and quickly assessed on cells obtained by fine-needle sampling of non-Hodgkin's lymphoma lesions. The present results suggest that in vitro radiation-induced apoptosis could be used as a predictive assay of early response to low-dose in vivo irradiation in patients with non-Hodgkin's lymphomas.

Effect of combination treatment of 15 cGy total body irradiation and OK-432 on spontaneous lung metastasis and mitogenic response of splenocytes in mice

We investigated whether the combination treatment of 15 cGy total body irradiation (TBI) and a streptococcal preparation, OK-432, synergistically suppresses spontaneous lung metastasis and augments phytohemagglutinin (PHA) and concanavalin A (Con A) responses of splenocytes in WHT/Ht mice. TBI with 15 cGy was carried out 20 days after subcutaneous injection of squamous cell carcinoma cells into a hind leg. Lung colony number was counted 40 days after tumor injection. For PHA and Con A responses, mice were killed 4 hr after 15 cGy TBI. The combination treatment of 15 cGy TBI and OK-432 was most effective when OK-432 was administered 2 days before 15 cGy TBI. The combination treatment decreased the lung colony number to 29.9% of the control number. OK-432 slightly increased the PHA and Con A responses, and 15 cGy TBI did not increase them. However, when these two were combined, the PHA and Con A responses were significantly increased to 393% and 278% of the control levels, respectively. It was suggested that TBI and OK-432 acted synergistically in suppressing the lung metastasis and mitogenic response of splenocytes.

Low dose palliative radiotherapy in low grade non-Hodgkin's lymphoma

The clinical picture of disseminated (stage 3 and 4) low grade non-Hodgkin's lymphoma (NHL) is one of continuing relapse. Management options include observation only in asymptomatic patients, single agent chlorambucil or localised radiotherapy in patients with symptomatic nodal disease. Radiation doses of 25-40 Gray in 10-20 fractions have been the standard approach in low grade NHL, but in 1994 Ganem et al. [Hematol. Oncol. 8: 225-233, 1994] reported the use of low dose radiotherapy (LDRT)--4 Gray in 2 fractions over 3 days--for the palliation of symptomatic disease in patients with disseminated, chemoresistant low grade NHL. We describe here our early experience with this schedule.

Suppressive effect of low dose total body irradiation on lung metastasis: dose dependency and effective period

The dose dependency and effective period of suppressive effects by low dose total body irradiation (TBI) in both artificial and spontaneous lung metastasis were investigated using murine squamous cell carcinoma. In the artificial lung metastasis of the tumour cells injected through a tail vein, the TBI of 0.15-0.20 Gy resulted in significant net suppression of lung colony formation. With this dose range, the effective period lasted for 12 h ranging from 9 h before to 3 h after the tumour cell injection. Similar suppressive effect was also observed in the spontaneous lung metastasis. These data suggest that careful assessment of effective dose and duration of low dose TBI on human metastasis could provide a new therapy to suppress clinical metastasis.

A phase I study of WR-2721 in combination with total body irradiation (TBI) in patients with refractory lymphoid malignancies

This Phase I study was designed to establish the maximum tolerated dose (MTD) of WR-2721 when given twice weekly with total body irradiation (TBI) in the treatment of patients with advanced refractory lymphoid malignancies and to define the toxicities of this combination and schedule. Patients eligible for this study had advanced recurrent indolent non-Hodgkin's lymphoma (NHL) or chronic lymphocytic leukemia (CLL). Patients had symptomatic or progressive disease, a performance status of 0, 1, or 2, and adequate bone marrow, hepatic, and renal function. Only patients failing one or two regimens of prior chemotherapy were eligible. Patients who had received prior extended field irradiation were ineligible. Patients received TBI twice weekly (Tuesday and Friday) to a total of 10 doses at 15 cGy/fx. WR-2721 was given intravenously over 15 min beginning 30 min before irradiation. The escalation of WR-2721 was Level 1: 740 mg/m2 and Level 2: 910 mg/m2. The MTD of WR-2721 was that dose which produced predictable and reversible toxicity and would not interfere with patient well-being. Seven patients were entered onto the study, three at 740 mg/m2 and four at 910 mg/m2. Five patients had CLL and two patients small lymphocytic NHL. No patient had hypotension or nausea requiring reduction in dose level or even interruption of infusion of WR-2721. At 740 mg/m2 no grade 3 or 4 toxicities related to WR-2721 were observed, but two patients could not complete treatment because of TBI-induced prolonged thrombocytopenia following treatments 5 and 8. One patient completed all 10 treatments. At 910 mg/m2 of WR-2721, two patients requested removal from study because of malaise, one after 5 cycles and one after 7 cycles. One patient completed all 10 treatments. One patient was treated with a modified schedule of 7 treatments of 20 cGy/fx and tolerated and completed all treatments but developed significant thrombocytopenia following completion of treatment. No patients had disease progression during treatment. The median survival was 11 months. This study indicates that WR-2721 given at 910 mg/m2 twice weekly with TBI is well tolerated for at least 5 treatments and that 910 mg/m2 of WR-2721 is the MTD with this regimen. In view of the importance of total radiation dose in achieving a response with TBI, a dose escalation study of TBI with 910 mg/m2 of WR-2721 should be performed in patients with indolent non-Hodgkin's lymphoma.

New approaches to the treatment of follicular lymphoma

The major avenues of clinical research into the treatment of follicular lymphoma, 'more, if so when?', interferon therapy, and antibody therapy, have been presented in the light of present knowledge about the clinical course of the disease. They must be seen within the context of the current philosophical approach to the illness, and the economic climate which prevails, at a time when new drugs, for example fludarabine (Leiby et al, 1987; Reman et al, 1988; Whelan et al, 1991), are showing promise, and differentiating agents are being tested in remission (Cunningham et al, 1985). There can be little doubt that the objective of future research should be to eliminate the disease altogether at the time of initial presentation, since patients entering remission and never having a recurrence have a far greater probability of longevity than those in whom recurrences occur (Lister, 1991). There can also be little doubt that when lymphoma is present and causing symptoms, treatment should be given, since survival is longer for those in whom a response is achieved, at least at presentation, and at first recurrence (Lister, 1991). Since the latter is sadly the reality for the majority, improving treatment at the time of recurrence must also be a priority. Time will tell whether any of the options presently under investigation will be appropriate at all, and if so when. It is certainly the case that some of them will be entirely inappropriate for some patients, because the risk of toxicity will outweigh the potential benefit, especially for the elderly. Further careful identification of prognostic variables may allow for individualization of therapy. It would be comforting to know that the newly found molecular marker of the disease would help us. Its absence may do--but its presence certainly does not, since t(14;18) containing cells may seemingly be present for many years of clinical normality (Price et al, 1991, in press). The challenge to find the right treatment at the right time--or perhaps to identify the 'right patient' for the therapy continues.

Long-term results of low dose total body irradiation for advanced non-Hodgkin lymphoma

Sixty-eight patients received fractionated low dose total body irradiation (LTBI) as treatment for non-Hodgkin lymphoma (NHL) at the Rotterdamsch Radio-Therapeutisch Instituut (RRTI) in the period 1973-1979. Ninety percent (61/68) of these patients had advanced disease (Stage III + IV). According to current malignancy grade classifications, 34 patients had low grade NHL, 10 intermediate, and 19 high grade. In 5 cases no exact grading was possible. LTBI was given 3 times a week, midline dose 0.1 Gy, using 6 or 25 MeV photons to a mean total dose of 1.78 Gy. Initial response rate for low, intermediate, and high grade NHL was resp. 84, 42, and 40%. The main prognostic factor for survival and recurrence-free survival (RFS) was malignancy grade. Probability of uncorrected survival at 10 years for low, intermediate, and high grade was resp. 34, 0 and 0%. Probability of RFS at 10 years was resp. 19, 0, and 0%. Neither stage nor sex had any influence on survival. Age was reversely correlated with survival, but was not correlated with RFS. Influence of prior therapy (18 patients) on survival and RFS was separately analyzed. Neither survival nor RFS of unfavorable histologic type NHL (high and intermediate grade) was influenced. On the other hand patients with a favorable histologic type NHL (low grade) had a significantly (p less than 0.05) better RFS if they received LTBI as initial treatment, but survival was not significantly influenced. RFS at 5 and 10 years of patients who received LTBI as first treatment was respectively 32% and 27%. No treatment related complications were noted. Subsequent chemotherapy in case of relapse was not hampered by previous LTBI. The high response rate and extended RFS, without maintenance therapy, makes LTBI a preferable first line treatment for patients with advanced stage low grade NHL.

Follicular non-Hodgkin's lymphoma

FL is usually widely disseminated at presentation and responds to radiotherapy, single agent chemotherapy and combination therapy. The disease pursues a remitting and relapsing course with continuing sensitivity to brief periods of treatment until a terminal phase of drug resistance, transformation, or bone marrow failure is reached. Newly recognized prognostic factors indicative of tumour bulk include hepatosplenomegaly, B symptoms, anaemia and abnormal liver function. Using these factors it is possible to identify those patients at first diagnosis for whom conservative management is appropriate and those with a much less favourable prognosis for whom experimental treatments are being investigated.

A phase II study of human rDNA alpha-2 interferon in patients with low grade non-Hodgkin's lymphoma

Thirty-five patients with a diagnosis of non-Hodgkin's lymphoma of low histological grade were treated with 2 X 10(6)/m2 of human rDNA alpha 2 IFN-a2 by subcutaneous injection. Treatment was continued until progressive disease was documented or one year of therapy had been given. None of the patients had to stop treatment because of toxicity and no treatment delays or suspensions of therapy were necessary as a consequence of myelosuppression. Thirty four patients were evaluable and seventeen (50%) obtained an objective response (2 CR, 15 PR) with a median duration of eleven months. Sixteen patients were untreated prior to receiving interferon but were felt to need some form of therapy rather than be suitable for a watch policy. Eleven of these patients responded (69%) with 95% confidence limits lying between 41% and 89%. No other pretreatment factors appeared to affect the likelihood of response. Single agent IFN-alpha 2 has significant activity in the low grade non-Hodgkin's lymphomata and warrants further investigation in this disease.

The combined modality therapy of diffuse histology non-Hodgkin's lymphoma with cyclophosphamide, adriamycin, vincristine, prednisone (CHOP) and total body irradiation

The combination of cyclophosphamide, adriamycin, vincristine, and prednisone (CHOP) alternating with total body irradiation (TBI) has been shown earlier to be effective therapy in patients with malignant lymphoma who have received prior chemotherapy and/or radiation therapy. A limited institutional pilot study was therefore done by the Southwest Oncology Group between October 1977, and November 1978 to test the benefit of this program in previously untreated persons with Stages 3 and 4 diffuse histology non-Hodgkin's lymphoma. Eleven evaluable patients with the following histologies were treated: 7 poorly differentiated, 2 with histiocytic, 1 with mixed lymphoma and 1 with well-differentiated morphology. CHOP was given in the following manner: cyclophosphamide 400 mg/M2 IV day 1, adriamycin 40 mg/M2 IV day 1, vincristine 2 mg IV day 1, and Prednisone 100 mg po daily X 5. Forty-five rad total body irradiation was delivered in three fractions on days 21, 23 and 25. Chemotherapy was repeated on day 42, etc., until four cycles of CHOP and three cycles TBI (135R) were delivered. Responses were seen in 8/11 patients (6 CR and 2 PR); 5 persons are currently alive and 6 are dead. Two of the living patients are alive with disease and the remainder are in unmaintained remission. Two persons died with no response and one died in complete remission of an unrelated illness. The median duration of remission is 15 months and the median survival for all patients is 48 months. The therapy was well tolerated with a mean nadir leukocyte count of 3,020 X 10(9)/microliters (range 1.2-5.5) and a mean nadir platelet count of 188 X 10(9)/microliters (range 016-270). As delivered, this program is capable of producing durable remissions and needs to be verified in a larger series of patients.

Multimodality therapy of favorable prognosis non-Hodgkin's lymphoma

Twenty-seven previously untreated patients with favorable prognosis non-Hodgkin's lymphoma were treated with a combination of total body irradiation followed by cyclophosphamide - vincristine - prednisone (CVP). The dose of total body irradiation was planned to be 150 rad followed by 6 cycles of chemotherapy. The complete response rate was 59%; the complete plus partial response rate, 93%. The 50% disease-free survival was 8 months. The actuarial projected 5 year survival was 60% and the disease-free survival at 5 years was 27%. The program was well tolerated by the majority of patients. It is possible for some patients with favorable non-Hodgkin's lymphomas to achieve prolonged periods of disease-free survival when treated with combinations of irradiation plus chemotherapy.

Stage III nodular lymphomas. Preliminary results of a combined chemotherapy/radiotherapy program

Since 1975, all histologic subtypes of Stage III and IIIE nodular lymphoma patients were treated with a combination of radiotherapy and multiple-agent chemotherapy consisting of cyclophosphamide, doxorubicin, vincristine, prednisone, and bleomycin (CHOP-Bleo). Fifty-eight patients were treated through 1979. Treatment consisted of two cycles of CHOP-Bleo alternating with sequential radiotherapy to clinically involved regions, and further CHOP-Bleo to a total of ten cycles. Radiotherapy doses ranged between 3000 and 4000 rad delivered in three to four weeks. Forty-six patients completed treatment. In the other 12 patients, treatment was interrupted because of progressive disease in seven, and myelosuppression in five. Overall five-year survival and disease-free survival results were 82% and 47%, respectively. Survival for those patients who completed therapy was 93%. By histopathology, survivals for all patients were: poorly differentiated lymphocytic, 100%; mixed cell, 80%; and histiocytic, 39%. Disease-free figures for all 58 patients were: poorly differentiated lymphocytic, 44%; mixed cell, 65%; and histiocytic, 35%. The extent of abdominal disease influenced five-year survival as follows: 100% for those who had only occult disease at staging laparotomy; 88% for those who were Stage III on the basis of a positive lymphangiogram; and 50% for those who had a palpable mass or required an exploratory laparotomy for symptoms. Five of seven patients with progression during protocol therapy have died. No patients died as a result of myelosuppression. A number of patients developed complications during treatment, none of which were fatal. Eight patients developed herpes zoster, four patients developed transient radiation hepatitis, and four patients had miscellaneous complications.

Total-body irradiation in advanced non-Hodgkin's lymphoma

Thirty-seven patients with advanced non-Hodgkin's lymphoma who were treated by total-body irradiation (TBI) at the Royal Marsden Hospital are reviewed. Twenty-four patients had received no previous therapy; 13 patients were in relapse. The overall response rate was 73% for nodular lymphomas and 80% for those with diffuse disease. THe duration of complete response ranged from two to 41 months (median 12 months). Subsequent chemotherapy was given successfully except in patients with prolonged thrombocytopenia which appeared to be related to an initially involved bone marrow. Hemibody irradiation (HBI) was the least myelosuppressive form of TBI and is now being used in complete remission following chemotherapy.

Stage III nodular lymphoreticular tumors (non-Hodgkin's lymphoma): results of central lymphatic irradiation

Since 1969, 29 previously untreated patients with Stage III nodular malignant lymphoreticular (MLT) have received total central lymphatic (TCL) irradiation. The volume irradiated included the entire abdomen, Waldeyer's ring, and preauricular nodes in addition to the usual regions encompassed by total nodal irradiation. Doses of 2000--3000 rads in three to six weeks were delivered to the nodal regions, liver, and spleen; fraction sizes ranged from 100 to 180 rads. Patients have been followed from one to ten years (median six years). The actuarial survival is 78% at five years, and the disease-free survival is 61%. There is no difference in disease-free survival of the patients with poorly differentiated lymphocytic vs. those with "histiocytic" or mixed cytology. Men and women had disease-free survivals of 82% and 43%, respectively. The long-term follow-up of these patients indicates that prolonged disease-free intervals are common after TCL irradiation, and some patients may be cured.

Total body irradiation as a secondary therapy in non-Hodgkin's lymphoma

Twenty-six patients with non-Hodgkin's lymphoma have received total body irradiation (TBI) as a secondary therapy. A response was achieved with 17 patients, in six of whom it was complete. The actuarial survival rates were 50% at one year and 42% at 30 months. Best results were achieved in those with low grade histology and in those under 60 years of age. Transient marrow toxicity was the only detected significant side-effect of treatment and although it was usually severe there were no serious sequelae. TBI should be considered as a secondary therapy in non-Hodgkin's lymphoma, regardless of previous treatment.