Findings from NSABP Protocol No. B-04: comparison of radical mastectomy with alternative treatments. II. The clinical and biologic significance of medial-central breast cancers

Findings from 1665 women with primary breast cancer, treated at 34 NSABP institutions in Canada and the United States, have failed to demonstrate that patients with medial-central tumors had a greater probability of developing distant metastases or dying than did those with lateral tumors despite the greater incidence of internal mammary (IM) node involvement when tumors are medial-central in location. A comparison of patients with similar clinical nodal status and tumor location who were treated either by radical mastectomy (RM) or by total mastectomy plus radiation therapy (TM + RT) failed to indicate that radiation of IM nodes reduced the probability of distant treatment failure (TF) or mortality. When findings from patients having equivalent clinical nodal status and tumor location treated by TM alone or TM + RT were compared, it was found that the addition of RT failed to alter the probability of the occurrence of a distant TF or of death. This was despite the fact that in the nonradiated group two putative sources of further tumor spread, i.e., positive axillary and IM nodes, were left unremoved and untreated. The findings provide further insight into the biologic significance of the positive lymph node and confirm our prior contention that positive regional lymph nodes are indicators of a host-tumor relationship which permits the development of metastases and that they are not important investigators of distant disease.

Disease-free survival at intervals during and following completion of adjuvant chemotherapy: the NSABP experience from three breast cancer protocols

Findings from the National Surgical Adjuvant Breast and Bowel Project (NSABP) trials evaluating three different regimens of adjuvant chemotherapy (L-PAM, L-PAM + 5-FU, L-PAM + 5-FU + MTX) in patients with primary breast cancer and positive axillary nodes indicate that each regimen has significantly contributed toward achieving the initial goal of such therapy, namely to diminish or prevent treatment failure in all or major subsets of patients during the first two years following operation when women are at greatest risk for a recurrence. Because of this hazard, chemotherapy was administered in all protocols for two years. Findings were examined at the end of the first year of therapy and at the termination of the second year for those who entered that year of therapy disease-free in order to determine whether the second year of treatment contributed a benefit beyond that achieved from the first year of therapy. A reduction in the incidence of treatment failure was evident in every subgroup of patients at completion of the first year of therapy. There was evidence of added improvement during the second year of treatment in patients aged 49 years or younger but not in those aged 50 years or older. Despite the finding, it is not possible from these studies to be absolutely certain that a second year of therapy is or is not advantageous. Findings obtained to date from the three studies indicate that patients completing two years of chemotherapy who are disease-free display a subsequent treatment failure rate that is no greater than that observed in untreated patients who survived two years without recurrence. Consequently, any advantage in disease-free survival observed at completion of therapy has been subsequently sustained for several years, suggesting this represents a real decrease rather than a postponement of treatment failure.

Treatment of primary breast cancer with chemotherapy and tamoxifen

We studied the possibility that the addition of tamoxifen to L-phenylalanine mustard combined with 5-fluorouracil enhances the benefit from the latter two drugs that has been observed in women with primary breast cancer and positive axillary nodes. Recurrence of disease was reduced at two years in patients given the three-drug regimen whose tumor estrogen-receptor levels were greater than or equal to 10 fmol. Among patients greater than or equal to 50 years old treatment failure was significantly reduced (P less than 0.001): by 51 per cent in those with one to three positive nodes and by 64 per cent in those with four or more. Higher receptor levels were associated with a greater probability of disease-free survival. Patients less than or equal to 49 years old were less responsive: those with one to three positive nodes received no benefit from tamoxifen at any receptor level, whereas those with four or more appeared to have reduced treatment failure associated with higher receptor levels. This adjuvant chemotherapy is not indicated in patients less than or equal to 49 years old whose tumor receptor levels are below 10 fmol; there is a suggestion of benefit in patients greater than or equal to 50 years old whose levels are low.

Acute toxicity during adjuvant chemotherapy for breast cancer: the National Surgical Adjuvant Breast and Bowel Project (NSABP) experience from 1717 patients receiving single and multiple agents

Since 1972, the National Surgical Adjuvant Breast and Bowel Project (NSABP) has carried out a series of clinical trials evaluating the worth of adjuvant chemotherapy in the management of patients with primary breast cancer. This report provides information concerning (a) protocol compliance relative to drug administration and (b) acute toxicity encountered by patients in three separate trials who were given one-, two- or three-drug chemotherapy within 1 month of operation. The findings are derived from 1548 women who received 20,765 courses of chemotherapy, the most extensively documented experience yet reported. They indicate that despite the large number of physicians and the heterogeneity of the institutions participating, large cooperative efforts can be accomplished with credibility. Only 13 (0.8%) of the women failed to complete all courses of therapy for reasons directly related to nonprotocol compliance by physicians. Only 4.3% failed to complete therapy for miscellaneous reasons other than toxicity, treatment failure, occurrence of a second primary, or death unrelated to tumor. While almost all patients experienced toxic reactions during the therapy, only 3%--4% of recipients of melphalan (L-PAM; P) and 4%--5% of recipients of L-PAM + 5-FU(F)(PF) failed to complete 2 years of therapy because of toxicity. Of those patients receiving PF + methotrexate (MTX; M) (PMF), 15% did not finish their treatment for that reason. While there was little difference in hematologic and nonhematologic toxicity between those patients receiving P or PF, and such toxicity was generally acceptable to both patients and physicians, the addition of MTX (PMF) resulted in greater toxicity (vomiting, stomatitis, and alopecia) which was less readily accepted. Tolerance of any of these regimens was unrelated to patient age, despite the belief that older women are less tolerant of chemotherapy. The earlier toxicity occurred, the greater was the number of subsequent courses associated with toxicity, and the lower was the total amount of drug received. The extent of the toxicity produced by the NSABP regimens and the end results obtained with them, must be compared with the end results and toxicity obtained by other regimens before making a choice of the adjuvant therapy to be used.

Laminated Marlex-methyl methacrylate prosthesis for massive chest wall resection

Room temperature-curing methyl methacrylate has been sandwiched between two layers of Marlex mesh and molded in the operating room to achieve chest wall stability following an extensive anterolateral resection. Reliable coverage with latissimus dorsi myocutaneous flap has made this simple, aesthetically pleasing, and firm reconstruction practical, even in a patient who received high-dose irradiation.

Cellular cytotoxicity in tumor-bearing mice after transfer of normal or tumor-sensitized lymphoid cells

The present investigations are a continuation of those indicating that the administration to normal inbred C3HeB/-FeJ mice of syngeneic tumor-sensitized cells or cells from F344 Mai rats (xenogeneic) sensitized to mouse tumor imparted "information" that resulted in the production of tumor-specific cytotoxic cells by recipients. Current findings revealed that normal but not tumor-sensitized spleen cells when transferred to syngeneic tumor-bearing recipients enhanced the cytotoxicity ofrom F344 Mai rats (xenogeneic) sensitized to mouse tumor imparted "information" that resulted in the production of tumor-specific cytotoxic cells by recipients. Current findings revealed that normal but not tumor-sensitized spleen cells when transferred to syngeneic tumor-bearing recipients enhanced the cytotoxicity of lymphoid cells in the recipients. This enhanced cytotoxicity was specific for the immunizing tumor. Inoculation of normal or tumor-sensitized lymph node cells failed to produce such an effect. Our present and previous findings suggested that in the presence of a tumor, uncommitted cells that reside in the spleen and that are available for recruitment and "instruction" may become depleted, whereas no comparable deficit may exist in cells that are capable of information transfer.

Cellular cytotoxicity and serum inhibition in normal mice following transfer of syngeneic tumor-sensitized cells

Investigations were performed to elucidate changes in normal syngeneic recipients after they received tumor-sensitized cells. Transfer of regional or nonregional lymph node cells or spleen cells from tumor-bearing inbred C3HeB/FeJ mice to normal syngeneic recipients caused the recipients to produced bone marrow, which mediated in vitro cytolysis of immunizing tumor target cells. This finding was not entirely limited to transfer of lymphoid cells. The transfer of myeloid cells, granulocytes, and cultured macrophages from tumor-bearing mice also produced cytotoxic cells. The extent of cytotoxicity following cell transfer was related to the duration of tumor growth in cell donors, to the degree of cytotoxicity, and to the number of cells transferred. Both the iv and ip routes were equally effective. Treatment of cells before transfer with trypsin or pronase, mitomycin C, or sublethal irradiation failed to prevent development of cytotoxicity in cells of the recipient, whereas freeze-thawing abolished this event. Serum from the cell recipient could inhibit the cytotoxicity demonstrated by lymphoid cells derived from the recipient or from a tumor-bearing animal. The findings indicate that "information" transferred to normal animals not previously exposed to a tumor results in production of tumor-specific cytotoxic cells in these animals.

Preliminary observations on the use of Corynebacterium parvum in patients with primary intracranial tumors: effect on intracranial pressure

It has been observed that patients with metastatic brain lesions developed neurologic symptoms when given Corynebacterium parvum. To obtain more information in patients with intracranial mass lesions, intracranial pressures (ICP) were measured or observed in six patients undergoing C. parvum therapy. All patients except two (one previously shunted, one recently operated) demonstrated a profound increase in ICP. It is presumed that either edema is formed within brain and tumor tissue (inasmuch as neurologic deterioration has not been observed in patients without an intracranial lesion) or transient increases in cerebral blood flow adversely alter an already compromised intracranial volume. Surgical decompression of tumor volume or use of Lasix may abort this response to C. parvum infusion.

The effect of Corynebacterium parvum in combination with 5-fluorouracil, L-phenylalanine mustard, or methotrexate on the inhibition of tumor growth

Previous reports from this laboratory have demonstrated conclusively that cyclophosphamide administered asynchronously with Corynebacterium parvum (CP) results in greater C3H mammary tumor inhibition than that observed with either agent alone. An analysis of this combination has revelaed that the chemotherapeutic component contributes more significantly to tumor inhibition than does the immunotherapeutic one. This study was conducted to investigate the inhibition of C3H mammary tumors by other chemotherapeutic agents when used with CP. The results have demonstrated that 60 mg of cyclophosphamide per kg, 90 mg of 5-fluorouracil per kg, and 10 mg of L-phenylalanine mustard per kg administrated weekly have similar tumor-inhibiting properties. The addition of CP enhanced the tumor-inhibiting properties of each agent but to differing degrees. The effect of the immunopotentiator when used in combination with alkylating agents was greater than that seen when it was used with the antimetabolite 5-fluorouracil. The tumor inhibition observed when cyclophosphamide was administered asynchronously with CP was significantly greater than that observed when L-phenylalanine mustard was similarly used. Of particular interest was the finding that the addition of CP to a combination of chemotherapeutic agents resulted in no greater tumor growth inhibition than that which occurred when CP was used along with the most effective single agent in the combination. The data have indicated that, contrary to clinical impression, there is no evidence that CP through its toxicity-sparing effect permits the utilization of larger doses of chemotherapy. Consideration has been given to the mechanisms that might account for the differences in tumor growth inhibition encountered when CP was used with different chemotherapeutic agents.

Further observations on the inhibition of tumor growth by corynebacterium parvum with cyclophosphamide

The cytotoxic macrophage was further characterized as an important effector cell in the inhibition of tumor growth. When we administered rifampin (a semisynthetic antibiotic that interferes with macrophage function but not viability) with Corynebacterium parvum and/or cyclophosphamide to tumor-bearing C3HeB/FeJ female mice, the tumor growth-inhibitory effects of the C. parvum were reduced. Moreover, when bone marrow cells from those animals were cultured, we found a marked decrease in the cytotoxicity of macrophages comprising clonies arising from colony-forming cells (CFC) in the bone marrow. Such findings supported our contentions that 1) the cytotoxic property of macrophages originates in ancestral stem cells or CFC in bone marrow, and 2) receptor sites of the CFC (or stem cells) that respond to a stimulus for self-replication probably differ from sites that when activated produce progeny with cytotoxic properties. Although the administration of rifampin resulted in macrophages virtually devoid of cytotoxic properties, both relative and absolute numbers of CFC increased.

Correlation of antitumor chemoimmunotherapy with bone marrow macrophage precursor cell stimulation and macrophage cytotoxicity

The present investigations have assessed the effects of prolonged cyclophosphamide (CY) and Corynebacterium (CP) treatment on the production of bone marrow macrophage precursors [colony-forming cells (CFC)] and on the cytotoxicity of macrophages comprising colonies produced by the CFC. The findings have been correlated with tumor growth in animals receiving the immunochemotherapy. In addition, studies have been directed toward ascertaining whether the administration of CP with CY might lessen the myelosuppressive effects of the latter. Following each consecutive weekly dose of CY (even after as many as 11), there was a significant depression in the number of bone marrow cells (BMC's) but, by the next injection, marrow cellularity had returned to normal. When the number of BMC's was reduced, the proportion of the remaining cells, which consisted of CFC, was increased. Upon reconstitution of the marrow, the proportion of CFC returned to the level of the controls. The total number of CFC in marrow was at no time following CY therapy significantly less than the number in marrow of untreated mice. The addition of CP to the treatment regimen with CY resulted in an absolute as well as relative increase in CFC at all times during administration of the combined therapy, i.e., when there was a depression in total numbers of marrow cells, as well as when marrow restoration had occurred. Although CP stimulated the number of cells entering into differentiation, it failed to affect the total numbers of marrow cells, as well as when marrow restoration had occurred. Although CP stimulated the number of cells entering into differentiation, it failed to affect the total BMC's had been neither increased nor prevented from decreasing, by CP administration, indicating that the use of total cellularity as an index of the CP marrow-sparing effect is without merit. The present results relative to cytotoxicity of macrophages derived from the CFC concur with and extend our previous findings indicating that the cytotoxic property of macrophages originates in its ancestral stem cell or CFC and that factors responsible for increasing the CFC population do not selectively stimulate precursor cells responsible for production of the cytotoxic macrophage. Although the proportion of cytotoxic macrophages was not altered by CP when administered with CY, the absolute number of such cells was increased. Since the increase in macrophage colony production and, consequently, in cytotoxic macrophages correlates with increased inhibition of tumor growth when CP was used with CY, it is suggested that macrophage precursors are the cells of primacy in CP immunopotentiation. Their stimulation, resulting in enhanced cytotoxic macrophage formation, could be responsible for the inhibition of tumor growth observed in our model system. The findings also suggest that when myelosuppression is a limiting factor in the use of a chemotherapeutic agent, the concomitant use of CP may be advantageous.

Observations following Corynebacterium parvum administration to patients with advanced malignancy. a phase I study

There has been increasing interest regarding the use of Corynebacterium parvum (CP) with other modalities in the management of primary cancer. Due to the paucity of specific information available relative to CP toxicity, a Phase I study was carried out in patients with advanced disease. The purpose of the investigation was not to evaluate the effect of CP on tumor growth. from 273 injections of CP in 40 patients it was observed that following intravenous (i.v.) infusion of CP: a) a febrile response and chills of considerable severity occured in almost all patients and did not appreciably diminish in intensity following repetitive administrations; b) nausea, vomiting, headache, and confusion were not infrequent; c) a "flu-like" syndrome lasting 24 to 48 hours occurred following almost all courses of CP; d) blood pressure elevations occurred on occasion and were related to the severity of other-side-effects; hyper- or hypo- tension was not a problem; e) ther were no anaphalactic reactions. Pretreatment with a single administration of 100 mg of hydrocortisone prior to CP infusion markedly and in some instances dramatically diminished the toxicity and made acceptable the use of i.v. CP on an outpatient basis. The use of i.v. CP in patients with cerebral metasteses may be hazardous. Subcutaneously administered CP resulted in a significant number of undesirable local reactions. Evaluation of delayed cutaneous hypersensitivity response, immunoglobulins, complement, and E- and EAC-rosette-forming cells during CP administration failed to demonstrate significant change from injection values. Results were similar whether hydrocortisone pretreatment was or was not employed. From the standpoint of toxicity it now seems appropriate to use i.v. CP, particularly following pretreatment with hydrocortisone, in a controlled clinical trial to evaluate its therapeutic effectiveness in the management of primary cancer.

The effect of a growing tumor and its removal on the cytotoxicity of macrophages from cultured bone marrow cells

Previous investigations by us have demonstrated that there is a significant but transient (4 to 14 days) increase of colony-forming cells (CFC) in bone marrow following implanation of a syngeneic mammary tumor in C3H mice. Those CFC gave rise to enhanced macrophage colony production when cultured in semisolid medium. The present studies have for the first time demonstrated that macrophages from the colonies were cytotoxic to cells from the immunizing tumor, and they continued to possess that characteristic for as long as a tumor was present in the animal from which bone marrow was derived. By 21 days after tumor removal cytotoxicity was no longer evident. The findings provide evidence to suggest that the cytotoxicity displayed by the macrophage originates in its ancestral CFC or in the antecedent stem cell. They also suggest that receptor sites of the CFC (or stem cell) that respond to a stimulus for self-replication are probably different from those sites that, when activated, result in cytotoxic properties of their progeny. The present findings also indicate not only that quantitation of macrophage production is of relevance in determining the efficacy of a therapeutic regimen but also that knowledge concerning the specific properties, i.e., ctytotoxicity, of such cells is of equal or greater importance.

Further observations on the inhibition of tumor growth by Corynebacterium parvum with cyclophosphamide. III. Effect of C. parvum on cyclophosphamide metabolism

Results of investigations employing [14C]cyclophosphamide (CY) demonstrated that even though total plasma radioactivity was similar in female C3HeB/FeJ mice treated either with CY alone or Corynebacterium parvum and CY, the proportion of total activity due to nonmetabolized CY was greater when C. parvum was used. These findings indicated that the antitumor effect of C. parvum may not have been entirely due to its immunopotentiating properties but may also have been related to its effect on the metabolism of CY.

Further observations on the inhibition of tumor growth by Corynebacterium parvum with cyclophosphamide. II. Effect of cortisone acetate

Studies from this laboratory have demonstrated that the administration of cyclophosphamide (CY) and Corynebacterium parvum (CP) over a prolonged time to C3H mice with established measurable tumors resulted in complete arrest of tumor growth as well as partial and complete regressions in many instances. A study of the effect of two different doses of cortisone acetate (CA), administered two or five times weekly, on the tumor inhibitory properties of this chemoimmunotherapeutic regimen indicated that the addition of a corticosteroid to the CY-CP combination did not alter its tumor-inhibitory properties. There was no significant change when CA was administered with CP; however, tumor inhibition was enhanced to a degree approaching statistical significance when CA was added to CY at dose levels of 1.5 and 2.5 mg twice weekly. These results demonstrated that it may be possible in treatment of humans to administer a steroid in combination with a chemoimmunotherapeutic regimen without inhibition of the regimen's antitumor effects.

Further observations on the inhibition of tumor growth by Corynebacterium parvum with cyclophosphamide. I. Variation in administration of both agents

Studies from this laboratory have indicated that the administration of cyclophosphamide (CY) and Corynebacterium parvum (CP) over a prolonged time to C3H mice with established measurable tumors resulted in complete arrest of tumor growth as well as partial and complete regressions in many instances. The present investigations on optimal dosage, route, frequency, and sequence of administration of CY and CP in the model system were performed to obtain information that could be useful in the design of chemotherapeutic and immunotherapeutic regimens for the treatment of human tumors. Findings have suggested the need for administration of CP in more than one instance. Although a single dose of CP in combination with weekly injections of CY had a significantly prolonged inhibitory effect, weekly doses of CP and CY were more effective. We also concluded that the time between doses of an immunostimulating agent (I-I interval) as well as between administration of chemotherapy (C-C interval) may be critical for an optimal result. In this model system, C-C and I-I intervals of 7 days inhibited tumor growth most effectively. The time between administration of chemotherapy and immunotherapy (C-I interval) has been considered critical. Whereas slightly better results were achieved in these studies when the immunotherapy was administered 4 days after the CY or when the C-I interval was +4 days, almost equally good results were obtained when both agents were given on the same day, which signified that the C-I interval may not be as critical as other investigators have reported. The present findings confirmed and extended our prior observations and indicated that the iv and ip routes of administration were superior to the im and sc routes in our model. The observed tumor growth inhibition was a result of both chemotherapeutic and immunotherapeutic modalities; also, the inhibitory properties of the regimen were more related to the chemotherapeutic component. Finally, almost identical tumor growth inhibition was observed when CP obtained from two different laboratories was used in conjunction with CY.

Studies concerning the regional lymph node in cancer. VIII. Effect of two asynchronous tumor foci on lymph node cell cytotoxicity

Results suggest that cytotoxicity by cells from nodes regional to a primary tumor is unique. While a primary tumor was present, A) cytotoxicity was displayed by cells from lymph nodes (RLNs) to that tumor, B) cells from nonregional lymph nodes regional (NRLNs) possessed lesser cytotoxicity which failed to increase in response to a second tumor focus in an area drained by those nodes, and C) the second focus attenuated cytotoxicity of cells from LNs regional to the primary tumor. Following removal of the primary tumor, cells from RLNs rapidly lost cytotoxicity and with passage of time were unable to regain that function in response to a second tumor focus. In contrast, cells from NRLNs demonstrated increased cytotoxicity at any time following removal of the primary tumor when exposed to a second focus. These observations suggest that nodes regional to a distant metastatic focus may be unable to react to it and thus contribute little to the host response generated by the primary tumor. In addition, since nodes regional to a primary tumor manifest diminished cytotoxicity in the presence of a distant tumor focus, tumor cells gaining access and lodging in those nodes subsequent to the development of other metastatic foci are likely to proliferate, resulting in the "positive" lymph node. The findings are in keeping with our contention that host factors responsible for metastases, and perhaps metastases themselves, are at least in part responsible for growth of tumor in RLNs. They also have relevance to the site of administration of specific immunotherapeutic agents and to the significance of the removal of RLNs with a primary tumor.

Ten year follow-up results of patients with carcinoma of the breast in a co-operative clinical trial evaluating surgical adjuvant chemotherapy

In 1958, a co-operative clinical trial, involving 23 institutions, was begun to evaluate the efficacy of a short course of triethylenethiophosphoramide as an adjuvant to radical mastectomy in the treatment of patients with primary carcinoma of the breast. Of 826 women prospectively randomized so that they received either a placebo or triethylenethiophosphoramide, 99.3 per cent were available for five years of follow-up study, and 95.3 per cent have been observed for ten or more years. Results have indicated the inadequacy of standard operative therapy in effecting a permanent tumor-free state in a majority of patients. Particularly distressing was the finding that 76 per cent of all patients with positive axillary nodes--65 per cent with one to three and 86 per cent of those with more than or equal to four positive--demonstrated a treatment failure by ten years and that only 24.9 per cent survived. The survival rate of those with one to three positive nodes was 37.5 per cent and only 13.4 per cent if more than or equal to four nodes contained tumor. Also disturbing was the observation that one of four patients with negative axillary nodes displayed a treatment failure by ten years. Such findings mandate the urgency for immediate evaluation of available systemic therapeutic agents postoperatively. That systemic chemotherapy can enhance the disease-free state as well as survival rate of at least some patients with carcinoma of the breast is supported by the finding that the original observation at 18 months indicating an advantage for premenopausal women with more than or equal to four positive nodes who received triethylenethiophosphoramide persisted for as long as ten years. At that time, 21 per cent fewer patients in the triethylenethiophosphoramide group had treatment failures and 21 per cent more survived, an indication that the initial delay in treatment failure was reflected in patient survival rate. Data suggesting that the limited chemotherapy used was more effective in patients having smaller tumors are in keeping with the concept that adjuvant therapy is likely to be most effective in a host with minimal residual tumor burden. Of importance was the observation that 80 per cent of treatment failures occurring in ten years were apparent by five years of observation. Strikingly, 86 per cent of ten year treatment failures in patients with positive nodes occurred by five years. In patients with more than or equal to four positive nodes, this was so in 92 per cent of the instances. Such findings tend to discredit the claim that the worth of an alternative treatment for carcinoma of the breast can be ascertained only by a period of observation much longer than five years.

L-Phenylalanine mustard (L-PAM) in the management of primary breast cancer. A report of early findings

Prolonged l-phenylalanine mustard (L-PAM) administration as an adjuvant to mastectomy in the management of patients with primary breast cancer and pathologically positive axillary nodes was evaluated by a prospective, randomized, clinical trial. Treatment failures occurred in 22 per cent of 108 patients receiving placebo and 9.7 per cent of 103 women given L-PAM (p = 0.01). A statistically significant difference (p = 0.02) existed in favor of L-PAM relative to disease-free interval. In premenopausal women, the difference with respect to disease-free interval of treated and control groups was highly significant (p = 0.008). A treatment failure occurred in 30 per cent of premenopausal patients receiving placebo and 3 per cent of those treated with L-PAM (p = 0.008). Whereas a similar trend was observed in postmenopausal patients, the difference is not statistically significant. Thus, L-PAM has been demonstrated to be effective in the treatment of women with primary breast cancer, particularly those who are premenopausal. Results were achieved with minimal undesirable side effects.

Inhibitory effect of prolonged Corynebacterium parvum and cyclophosphamide administration on the growth of established tumors

The present study was carried out to investigate the effects of prolonged administration of C. parvum alone and in combination with cyclophosphamide for the treatment of established, measurable C3H tumors. The continued weekly administration of C. parvum by itself provided a limited but significant inhibitory effect on tumor growth and significantly prolonged survival. Intraperitoneal and intravenous administration was found to be more effective than the subcutaneous route. When C. parvum was administered asynchronously in combination with cyclophosphamide at weekly intervals a tumor growth inhibitory effect was achieved which was greater than that resulting from either agent along. Such an effect was consistently obtained and was seemingly independent of the sequence of drug administration. When cyclophosphamide preceded the initial C. parvum administration, arrest in the rate of tumor growth occurred, resulting in infinite tumor doubling time for the duration of observation (greater than 90 days). The combination of C. parvum and cyclophosphamide produced a more effective inhibition of tumor growth than did BCG and cyclophosphamide similarly employed. The importance of these findings relative to clinical application is considered. While the significance and genesis of the marked desmoplastic reaction characterizing tumors from animals treated with C. parvum and cyclophosphamide is at present speculative, consideration is given to the possibility that this could signify a host response against tumor growth.