Prolongation of postoperative disease-free interval and survival in human colorectal cancer by B.C.G. or B.C.G. plus 5-fluorouracil

Targeting nucleotide metabolism: a promising approach to enhance cancer immunotherapy

Targeting nucleotide metabolism can not only inhibit tumor initiation and progression but also exert serious side effects. With in-depth studies of nucleotide metabolism, our understanding of nucleotide metabolism in tumors has revealed their non-proliferative effects on immune escape, indicating the potential effectiveness of nucleotide antimetabolites for enhancing immunotherapy. A growing body of evidence now supports the concept that targeting nucleotide metabolism can increase the antitumor immune response by (1) activating host immune systems via maintaining the concentrations of several important metabolites, such as adenosine and ATP, (2) promoting immunogenicity caused by increased mutability and genomic instability by disrupting the purine and pyrimidine pool, and (3) releasing nucleoside analogs via microbes to regulate immunity. Therapeutic approaches targeting nucleotide metabolism combined with immunotherapy have achieved exciting success in preclinical animal models. Here, we review how dysregulated nucleotide metabolism can promote tumor growth and interact with the host immune system, and we provide future insights into targeting nucleotide metabolism for immunotherapeutic treatment of various malignancies.

Implantable Synthetic Immune Niche for Spatiotemporal Modulation of Tumor-Derived Immunosuppression and Systemic Antitumor Immunity: Postoperative Immunotherapy

The development of biomaterial-based immune niches that can modulate immunosuppressive factors in tumor microenvironment (TME) will be a key technology for improving current cancer immunotherapy. Here, implantable, engineered 3D porous scaffolds are designed to generate synergistic action between myeloid-derived suppressor cell (MDSC)-depleting agents, which can accommodate the establishment of a permissive immunogenic microenvironment to counteract tumor-induced immunosuppression, and cancer vaccines consisting of whole tumor lysates and nanogel-based adjuvants, which can generate tumor antigen-specific T cell responses. The local peritumoral implantation of the synthetic immune niche (termed immuneCare-DISC, iCD) as a postsurgical treatment in an advanced-stage primary 4T1 breast tumor model generates systemic antitumor immunity and prevents tumor recurrence at the surgical site as well as the migration of residual tumor cells into the lungs, resulting in 100% survival. These therapeutic outcomes are achieved through the inhibition of immunosuppressive MDSCs in tumors and spleens by releasing gemcitabine and recruitment/activation of dendritic cells, enhanced population of CD4⁺ and CD8⁺ T cells, and increased IFN-γ production by cancer vaccines from the iCD. This combined spatiotemporal modulation of tumor-derived immunosuppression and vaccine-induced immune stimulation through the iCD is expected to provide an immune niche for prevention of postoperative tumor recurrence and metastasis.

Adjuvant therapy of cancers of the colon and rectum

Important advances have been made in our understanding of the role of adjuvant therapy for colorectal cancer. Current standard 5FU-based regimens have been convincingly shown to reduce the incidence of recurrences and to prolong overall survival in patients with resected stage III colon cancer. Colon cancer patients with stage II disease have a better-overall prognosis than those with stage III; however, the relative merits of adjuvant treatment in these patients remains controversial. Combined chemotherapy plus radiation therapy is currently the standard adjuvant approach for stage II and III rectal cancer patients. Despite the advances that have been made, far too many patients with resectable colorectal cancer ultimately relapse and die of their disease. There remains a pressing need for continued development of improved adjuvant treatments. Participation of eligible patients in clinical trials must continue to be actively encouraged. Only in this way will we be able to continue to build and expand on the progress that has been made thus far.

Immunomodulation therapy in colorectal carcinoma

There has been much progress in the understanding of the relationship between the immune system and colorectal cancer. This has led to the use of immunomodulatory therapy in the adjuvant and palliative treatment of the condition. Although attempts at the use of non-specific immunomodulation with agents such as levamisole, cimetidine, alpha interferon and Bacillus Calmette-Guerin (BCG) have not produced significant clinical benefits when tested in randomized trials in both the adjuvant setting and for metastatic disease, promising results are being obtained with more specific therapy. Edrecolomab [corrected], a murine monoclonal antibody targeting the 17-1A antigen on malignant colorectal cells has produced a reduction in relapse and mortality rates when used as adjuvant treatment following surgery for Dukes' C colon cancer. Active specific therapy with autologous tumour vaccine administered with BCG has produced similar benefits in Dukes' B cancer. Both 3H1 anti-idiotypic antibody against carcinoembryonic antigen and 105AD7 antibody to gp72 glycoprotein have demonstrated in-vitro and in-vivo immune activation against tumour. Non-randomized studies postulate prolongation of survival using these antibodies in advanced disease. These agents are all currently being tested in randomized studies powered to detect meaningful survival differences and clinical benefit. Immune therapy offers the potential of low toxicity therapy in colorectal cancer and may have a role as an adjunct to conventional chemotherapy.

Immunotherapy for colorectal cancer

BACKGROUND

Advances in molecular biology have enabled specific antigens present on colorectal cells to be characterized, against which immune responses may be generated. This, in combination with our inability to significantly alter survival from this condition, has resurrected an interest in immunotherapy as a potential treatment option.

DATA SOURCES

The information contained in this review was obtained following a search of MEDLINE and BIDS (Bath Information Data System), using the key words immunotherapy, colorectal cancer, antibody, anti-idiotype, peptide vaccine, viral vector, and vaccine. In addition, journals related to this field were systematically searched.

CONCLUSION

A number of approaches currently constitute immunotherapeutic options for colorectal cancer. A number of treatment modalities are already in phase III studies, although clearly not all will fulfill their initial promise. Surgeons need to be aware of the advances in this rapidly expanding field, and keep an open mind as to their efficacy.

Randomized, controlled study on adjuvant immunochemotherapy with PSK in curatively resected colorectal cancer. The Cooperative Study Group of Surgical Adjuvant Immunochemotherapy for Cancer of Colon and Rectum (Kanagawa)

A randomized, controlled trial of adjuvant immunochemotherapy with PSK (Kureha Chemical Industry Co., Tokyo, Japan) in curatively resected colorectal cancer was studied in 35 institutions in the Kanagawa prefecture. From March 1985 to February 1987, 462 patients were registered. Four hundred forty-eight of those patients (97.0 percent) satisfied the eligibility criteria. The control group received mitomycin C intravenously on the day of and the day after surgery, followed by oral 5-fluorouracil (5-FU) administration for over six months. The PSK group received PSK orally for over three years, in addition to mitomycin C and 5-FU as in the control group. At the end of February 1990, the median follow-up time for this study was four years (range, three to five years). The disease-free survival curve and the survival curve of the PSK group were better than those of the control group, and differences between the two groups were statistically significant (disease-free survival, P = 0.013; survival, P = 0.013). These results indicate that adjuvant immunochemotherapy with PSK was beneficial for curatively resected colorectal cancer.

Resident research award: tumor necrosis factor alpha selectively enhances growth and cytotoxic activity of tumor infiltrating lymphocytes from human colorectal cancer

Adoptive immunotherapy with tumor-infiltrating lymphocytes (TIL) and interleukin-2 (IL2) can induce regression of tumor metastases in animal models and in human metastatic malignant melanoma. We investigated the potential of colorectal cancer TIL as a source of killer cells and the effect of tumor necrosis factor alpha (TNF alpha) in combination with IL2 on their cytotoxic activity. Tumor-infiltrating lymphocytes were isolated from surgical specimens using a mechanical and enzymatic dissociation process. Autologous lamina propria mononuclear cells (LPMC) were used as control. Tumor-infiltrating lymphocytes and LPMC were cultured in the presence of IL2 with/without TNF alpha (1000 U/ml each) for 5 to 8 weeks. Cytotoxicity (% lysis) was tested against Daudi target cells in a 4-hr 51Cr-release assay. The combination of IL2 and TNF alpha resulted in a significantly greater-fold expansion of TIL than IL2 alone (P less than 0.01). Lamina propria mononuclear cells expanded less than TIL, and TNF alpha had an inhibitory effect on their growth (P less than 0.05). Tumor-infiltrating lymphocytes and LPMC showed comparable cytotoxicity when cultured with IL2 alone. However, the addition of TNF alpha augmented the killer activity of TIL while inhibiting that of LPMC (P = 0.035). These results indicate that TNF alpha selectively increases the IL2-induced growth and cytotoxic function of colorectal cancer TIL, but not those of gut mucosal lymphoid cells, suggesting that TIL and LMPC differ in their response to TNF alpha. Therefore, this combination of cytokines may hold more promise than single agents for the immunotherapy of colorectal cancers with TIL.

BCG and the treatment of superficial bladder cancer

In this report, we review the evolution of bacillus Calmette-Guérin (BCG) immunotherapy as a legitimate form of treatment in superficial, nonmuscle-invasive bladder cancer. In the US, an estimated 45,000 new cases of bladder cancer are diagnosed each year and the annual death rate approaches 11,000. Approximately 70 percent of these cancers are superficial at the time of initial presentation. The treatment of superficial bladder cancer has three objectives: (1) eradication of existing disease, (2) prophylaxis against tumor recurrence, and (3) prevention of tumor progression (either muscular invasion, metastatic spread, or both). Cystectomy generally is reserved for muscle-invasive disease. Transurethral resection of the bladder tumor is the preferred initial therapy. Intravesical instillations of various chemotherapeutic agents following transurethral resection have been extensively investigated. Some of the common agents used include thiotepa, mitomycin, and doxorubicin. Despite such treatment efforts, however, over 40 percent of patients with superficial bladder cancer experience a recurrence of their tumor within three years. Approximately half of these recurrences either present as less-well-differentiated tumors or have already penetrated into the bladder musculature, metastasized, or both. Since Morales et al. first introduced intravesical BCG vaccine for prophylaxis as well as for treatment of superficial bladder tumors in 1976, support has grown rapidly for its use as an alternative to chemotherapy. When used with prophylactic intent following transurethral resection, recurrence rates are lower than those achieved with other agents. In addition, BCG is emerging as the consensus drug of choice for treating carcinoma in situ of the bladder. The mechanisms by which BCG exerts its antitumor activity remain largely unknown. BCG is thought to stimulate a localized, nonspecific inflammatory response that leads to subsequent shedding of tumor cells. A large body of clinical and experimental data suggest an association between the development of an immunologic response to BCG and successful antitumor activity. No universally accepted therapeutic regimen has been agreed upon. One regimen commonly used consists of an ampul of BCG mixed with 50 mL of NaCl 0.9%, instilled once a week for six weeks and retained for two hours prior to voiding. Maintenance therapy generally consists of intravesical doses given at three-month cycles for at least two years of recurrence-free follow-up. Because BCG is a biologic agent, the commercially available products may differ in weight, colony-forming units per vial, and antigenicity. How these product characteristics affect clinical responsiveness to different strains of BCG remains unanswered.

Adjuvant chemoimmuno- and immunotherapy in Dukes' stage B2 and C colorectal carcinoma: a 7-year follow-up analysis

A prospectively randomised controlled clinical trial of adjuvant therapy was undertaken, at a single-centre, population-based cancer institute, in patients with Dukes' stages B2 and C colorectal carcinoma after curative surgery. Between 1976 and 1983, 253 patients were randomised to either control (no further therapy after surgery), immunotherapy (oral bacille Calmette-Guérin [BCG] 120 mg once a month) for 5 years or chemoimmunotherapy (oral BCG as above with methyl-cyclohexyl-chloroethyl nitrosourea [meCCNU] 130 mg/m2 on day 1 and 5-fluorouracil [5-FU] 325 mg/m2/day on days 1-5 and 375 mg/m2/day on days 36-40) repeated every 10 weeks for 8 cycles. The median follow-up of patients is now 6.95 years. Of the control, immunotherapy, and chemoimmunotherapy groups 22.35%, 39.28%, and 28.57%, respectively, have relapsed. The log-rank analysis of results shows no disease-free or overall survival advantage for patients receiving adjuvant therapy compared with the control group. Patients receiving adjuvant immunotherapy for stage B2 appear to have a significantly inferior disease-free survival compared with other groups, but their overall survival is similar. There are no significant differences in disease-free or overall survival in the three groups of patients with stage C tumour. Of 82 patients dying, 78.05% died of progressive colorectal carcinoma, 13 patients developed a second malignancy; the remainder died of seemingly unrelated causes.

Adjuvant therapy of poor prognosis colon cancer with levamisole: results of an EORTC double-blind randomized clinical trial

From 1978 to 1985, 297 patients were entered in a double-blind randomized trial comparing levamisole to placebo as adjuvant therapy of Dukes' C carcinoma of the colon. Therapy consisted of from two to five tablets of 50 mg levamisole (or placebo) twice a week, depending on bodyweight for 1 year. Levamisole was generally well tolerated, with only four reversible cases of agranulocytosis reported among 129 patients. The trial failed to show a benefit of levamisole on disease-free survival (P = 0.53) or on survival (P = 0.35). There was no difference between the two treatment groups in terms of number of disease relapses, sites of relapse, or time to relapse. The proportion of patients still alive at 5 years was 51 per cent (standard error, 5.5 per cent) in the levamisole group versus 39 per cent (standard error, 5.4 per cent) in the placebo group.

Controlled clinical trial of adjuvant immunotherapy with BCG and neuraminidase-treated autologous tumour cells in large bowel cancer

A controlled, randomised clinical trial of immunotherapy was performed in 301 patients with stage B or C colorectal cancer. The immunotherapy treatment consisted of 18 vaccinations over a 2 year period following surgery with a combination of BCG given by scarification plus subcutaneous injection of Vibrio cholera neuraminidase (VCN)-modified autologous tumour cells. Five year follow-up has now been completed in all patients. The immunotherapy did not alter either the disease-free interval or the overall survival of patients in comparison with a control group of patients not receiving immunotherapy.

Lymphokine-activated killer (LAK) cells from human intestinal mucosa: cytotoxic activity against tumor cell lines and modified self but not autologous and allogeneic colon cancer cells

Patients with colorectal cancer respond poorly to in vivo immunotherapy with lymphokine-activated killer (LAK) cells generated from peripheral blood mononuclear cells (PBMC). We postulated that gut-derived immune cells could be a more relevant source of LAK cells directed against colorectal cancer. Intestinal lamina propria mononuclear cells (LPMC) and colonic adenocarcinoma cells were isolated from operative specimens by combination of mechanical and enzymatic dissociation methods. LAK cells were generated by culturing PBMC and LPMC with recombinant interleukin 2 (IL2), with and without OKT3 monoclonal antibody, in short- (4 days) and long-term (21 days) cultures. Other cultured tumor cells, normal intestinal fibroblasts, and hapten-modified autologous LPMC were used as control targets. Cytotoxicity was measured by a 4-hr 51Cr release assay. Short-term cultured LAK cells exhibited a strong to moderate degree of killing against normal intestinal fibroblasts, hapten-modified self cells, and four different tumor cell lines. Instead, fresh colon cancer cells were resistant to cytotoxicity, regardless of their degree of histologic differentiation and the autologous or allogeneic nature of the LAK cells. Long-term culture with IL2 remarkably increased LAK cell activity against all tumor targets, but not against colonic adenocarcinoma cells. The results of this study, showing that freshly isolated colon cancer cells are intrinsically resistant in vitro to highly activated cytotoxic effector cells, may explain the poor clinical results observed in human trials with in vivo administration of IL2 or LAK cells.

Melbourne trial of adjuvant immunotherapy in operable large bowel cancer

A controlled randomized clinical trial was undertaken to assess the ability of combined non-specific and specific immunotherapy to alter the disease-free interval and overall survival of patients with Stage B or C large bowel cancer. The immunotherapy consisted of a 2 year programme of vaccinations with BCG and neuraminidase-treated autologous tumour cells. Three hundred and one patients entered the trial. At 5 years of follow-up there is no evidence that this form of immunotherapy can alter either the disease-free interval or survival in this group of patients.

Role of chemotherapy in the treatment of colorectal carcinoma

Large bowel cancer afflicts more patients in the United States than any other malignancy excluding skin cancer. Fifty percent of patients who undergo resection of colorectal carcinoma have positive lymph nodes, and approximately 18% have liver metastases at initial presentation. To improve survival, more effective treatment than surgical resection of the primary must be developed. The most active single agent in the treatment of colorectal carcinoma is 5-fluorouracil (5-FU). To increase the response rate obtained with this agent, work has been done on the modulation of 5-FU by other agents, using drugs that are synergistic with 5-FU and manipulating the method of 5-FU administration. Combination chemotherapy has improved response rates in some situations, though generally it has not been shown to improve survival. Studies using direct hepatic infusion clearly demonstrate an increase in response rates, but again, it is too early to say whether this type of treatment increases survival. Early adjuvant chemotherapy trials used inadequate doses of chemotherapy for short periods of time and demonstrated no added efficacy to surgery alone. Later studies with more aggressive therapy suggested some benefit to treating patients with rectal carcinoma; however, there is still little evidence that adjuvant chemotherapy improves survival in patients with colon carcinoma. To compare and understand the various chemotherapy trials, more stringent reporting of baseline laboratory values, performance status, and estimation of tumor involvement are needed.

A randomized controlled trial of adjuvant portal vein cytotoxic perfusion in colorectal cancer

In this randomized trial adjuvant cytotoxic portal vein perfusion in patients undergoing surgery for colorectal cancer without liver metastases was assessed to determine whether the incidence of metachronous liver metastases could be reduced and survival thereby improved. There were 127 control patients and 117 patients who received adjuvant perfusion. A further 13 patients were excluded following randomization because of cirrhosis in 1, liver metastases at laparotomy in 3 and technical problems with cannulation in 9. Dukes' staging and degree of differentiation were similar in the two groups. There were fewer liver metastases in the perfusion patients and overall survival was improved. However, the benefit appears to be greatest in patients with Dukes' B colon cancer.

Role of macrophage in the defense against intestinal cancers

The capability of activated macrophages to kill tumor cells in vitro is now well documented. The tumoricidal activation of macrophages against intestinal tumor cells by different agents is described and the main hypothesis on the mechanisms of tumor cell killing in vitro are discussed. These in vitro results suggest that the macrophage can constitute an efficient effector cell in the defense against intestinal tumors. The distribution and ratio of macrophages in normal intestine and intestinal tumors is described. At the moment, potent activators of macrophages studied in vivo on experimental and human intestinal tumors give poor results or even enhance the growth of tumors. Macrophages may also interfere with the specific immune response in two directions by enhancing the immune response or decreasing it by elaboration of mediators such as prostaglandins.

Adjuvant therapy of colon cancer--results of a prospectively randomized trial

After curative surgical resection, 621 patients with modified Dukes' stage B2, C1, or C2 colon carcinoma were randomly assigned to one of four treatment programs. These included chemotherapy with fluorouracil and semustine, immunotherapy with methanol extraction residue of bacillus Calmette-Guérin (BCG), combination therapy with fluorouracil, semustine, and immunotherapy, or close follow-up without adjuvant treatment. Treatment continued for 70 weeks. After a median of 51/2 years of follow-up, no significant differences were noted in either recurrence or survival rates among the four treatment programs. Leukemia developed in seven patients, all of whom had received fluorouracil and semustine. The results of this study do not support the use of chemotherapy with fluorouracil and semustine, immunotherapy with methanol extraction residue of BCG, or their combination as an adjuvant treatment program for patients at high risk for recurrent colon carcinoma. The data do, however, demonstrate the necessity for an untreated control group in a trial of adjuvant therapy for colon cancer.

Immunotherapy of colon cancer: prospects for developing immunogenic vaccines based on autologous serological typing

Exploration of specific immunization as a means of cancer therapy has been hampered by the lack of knowledge of human cancer antigens. Recent progress in the serological definition of cell surface antigens of malignant melanomas, renal cancers, and astrocytomas provides a new basis for the construction of immunogenic vaccines and their clinical testing. Application of the same approach to colon cancer depends on the development of methods which permit continuous growth of colon cancer cells in tissue culture.

A new approach in the immunotherapy of carcinoma of the colon and rectum

Although the therapy of carcinoma of the colon and rectum has been investigated, little progress has been made in prolonging the survival in these patients. Specific active immunotherapy may provide the answer. Previous investigators have shown that colorectal cancer elicits an immune response and may be susceptible to immunologic manipulation. My laboratory has shown that a live vaccinia virus-augmented (vaccinia oncolysate) tumor cell vaccine is safe and may be worthwhile in the surgical adjuvant treatment of colorectal cancer. Nine patients with advanced cancer were treated. 0/9 showed adverse effect and 3/9 showed lack of progression of disease. Randomized prospective trials are now underway.

The clinical correlation of an autopsy study of recurrent colorectal cancer

The complete autopsies of 145 patients dying of colorectal cancer are reviewed. Isolated local or distant metastases are infrequent, compared to disseminated disease. Solitary local recurrences are most common after resection of rectal tumors. Right colon tumors spread to local and distant sites in 90% of autopsies, and to distant sites alone in 10%. Rectal tumors spread locally only in 25% of cases, to distant site alone in 25%, and to both in 50%. Regardless of the origin of the primary tumor, the liver is the most common site of metastasis, followed by the regional lymph nodes and the lungs. Two-thirds of the patients with right colon lesions died of liver metastases, and three-quarters of those with rectal tumors succumbed to disseminated disease. The current curative and palliative treatment of recurrent colorectal cancer in clinical medicine by surgery, radiotherapy, and chemotherapy is reviewed. It is suggested that an understanding of the anatomic patterns of cancer recurrence will increase in importance as advances in the modalities of treatment are made,

Adjuvant immunotherapy of lung cancer with BCG cell wall skeleton (BCG-CWS)

Four hundred fifty-five patients with lung cancer were treated with oil-attached cell-wall skeleton of bacillus Calmette-Guérin (BCG-CWS) as adjuvant immunotherapy following initial conventional therapy. The overall survival period of the patients was prolonged significantly as compared with that of 380 patients in a historical control group receiving initial conventional therapy alone (p less than 0.0001). The prolongation of the survival period of the patients was also statistically significant when classified according to clinical stages and histological cell types. The therapeutic effect was remarkable in patients combined with malignant pleurisy. Intrapleural injection of BCG-CWS resulted in not only prevention of accumulation of pleural effusion and abrogation of tumor cells but also in prolongation of survival period (P = 0.016). No serious side effects due to BCG-CWS were experienced. From the previous experimental studies and clinical experiences with human tumors, it can be concluded that adjuvant immunotherapy with BCG-CWS is a useful therapeutic modality for lung cancer, especially in cases combined with malignant pleurisy.

Clinical trials of immunotherapy: present status

This brief review of the more promising clinical trials suggests that immunotherapy is indeed beneficial for selected cancer patients. Because of its limited potency, it should not be used as primary treatment for malignant disease except as local immunotherapy for certain accessible tumors. It is effective for eradication of primary neoplasms of the skin as well as cutaneous metastases of malignant melanoma and breast carcinoma. The most important role for immunotherapy is in combination with other modalities. It may help control occult micrometastases that cause recurrence and death following surgical procedures or irradiation. Results of adjuvant immunotherapy appear promising for malignant melanoma, for carcinoma of the lung, breast, and colon, and for soft-tissue sarcomas. In combination with chemotherapy, immunotherapy appears to prolong remission and survival in acute myelogenous leukemia and in disseminated tumors of the lung and breast. Clearly, immunotherapy is not a panacea for malignant disease, but it could become an important arm in a multimodality attack on cancer.

Reversible elevation of plasma CEA associated with iatrogenic unilateral hydronephrosis in a patient operated for colorectal cancer

A patient is reported with progressively rising plasma levels of CEA in association with iatrogenic, unilateral hydronephrosis, subsequent to surgery for colorectal cancer. The CEA level returned to normal with spontaneous recovery of the hydronephrosis. The knowledge of this association should serve as an additional guideline when a "second-look" operation is being considered in colorectal cancer patients (who have been previously rendered free of disease by pelvic surgery) when plasma CEA begins to rise progressively.

Disseminated BCG disease associated with immunotherapy by scarification in acute leukemia

Disseminated BCG infection developed in a patient with acute leukemia receiving BCG immunotherapy by scarification. Predisposing factors included the underlying malignancy, intensive chemotherapy, and continuous high-dose corticosteroids. The scarification technique is safe; however, physicians should be alert to this syndrome as a cause of fever of unknown origin in cancer patients receiving BCG immunotherapy.

Chemoimmunotherapy in disseminated melanoma and colorectal carcinoma

Non-specific immunotherapy with monthly intramuscular injection of Corynebacterium parvum has been investigated by randomized clinical trials in patients with advanced cancer. Thirty-six patients with disseminated melanoma were treated with either imidazole carboxamide (DTIC) alone or DTIC plus C.parvum. A 19% objective response rate was observed. The mean survival time was similar for both groups. Thirty-three patients with disseminated colorectal cancer were treated with either 5-fluorouracil (5FU) alone or 5FU plus C.parvum. No objective responses were observed. The mean survival time was similar for both groups. No advantage has been demonstrated in either tumour group by adding C.parvum to standard chemotherapy.

Chemotherapy and chemoimmunotherapy of colorectal cancer. Role of the carcinoembryonic antigen

The current status of treatment for patients with colorectal cancer is suboptimal. Although approximately 80% of patients are amenable to surgery, cure is only possible for 40%. Survival of patients is closely related to disease staging at the time of surgery, being poorer for patients presenting with locally advanced disease or with distant metastases. Patients who undergo curative resections and are categorized as having a high risk of developing recurrence, such as those with regionally involved lymph nodes, should be subjected to studies of adjuvant therapy. Although the definite role of such studies is still under evaluation, there already exist studies of chemotherapy with 5FU, chemoimmunotherapy with 5FU-BCG, and radiation therapy, suggesting the beneficial effect of these treatment modalities based on prolongation of the disease-free interval and survival of patients. The status of available treatments for patients with advanced disease is poor. There exists no single or multidrug regimen capable of producing significant tumor regression to improve the patient's quality of life and survival. Accordingly, the active clinical investigation of newer and potentially effective chemotherapeutic agents should continue. The role of present immunotherapy is not fully determined, although several studies suggest its potential usefulness in the adjuvant and the advanced situations. Serial determinations of CEA are extremely helpful in the postsurgical monitoring of patients receiving adjuvant treatments and also in the follow-up of patients undergoing therapy for overt metastatic disease.

Adjuvant immunotherapy and chemoimmunotherapy in colorectal cancer (Dukes' class C): prolongation of disease-free interval and survival

The poor postsurgical prognosis in patients with colorectal cancer of the Dukes' C classification has prompted a clinical trial of adjuvant immunotherapy versus chemoimmunotherapy intended to prolong either the disease-free interval or the overall survival or both. One hundred and twenty-one patients have been entered on this study. Fifty-two patients received BCG alone and 69 patients received the combination of 5-FU and BCG. The disease-free interval and the overall survival were compared with similar parameters in a group of historical controls with similar prognostic characteristics who were operated on in our institution prior to the initiation of the current study. There was no difference as yet between BCG alone and the combination of 5-FU + BCG in terms of both the disease-free interval and the survival. Both treatments, however, had significantly better results than the surgical controls. Adjuvant therapy, especially with BCG is advocated for patients with colorectal carcinoma, Dukes' C class, following potentially curative surgery.

The modulation of tumour-versus-host response in lung, colon, and breast cancer patients: implications for adjuvant immunochemotherapy

Major advances in the understanding of clinical tumour biology occurred with the appreciation that tumour-associated substances circulated in the blood of cancer patients. In this study their origin and immunogenic function have been investigated. Whole tumour cells (WTC) and cancer cell membrane fractions (CMF) of 24 patients with lung, colon, and breast cancer were investigated for their antigenic effect upon the patients' own lymphocytes and upon healthy allogeneic ones. The antigenicity of whole lung and breast cancer cells to stimulate lymphocyte DNA synthesis, and the ineffectiveness of colon cells were confirmed. CMF had little stimulating effect upon autologous lymphocytes; however, they were able to augment lymphocyte response to PPD and PHA in high dilution and to suppress it in high concentration. The serum of cancer patients exerted similar biphasic activity upon PPD and PHA stimulated lymphocytes ("lymphosuppressive-stimulatory factors", or LSSF). Sephadex studies confirmed that LSSF activity in cancer serum correlated with circulating CMF. These substances modulate lymphocyte nucleic acid synthesis in vitro; it is likely that they similarly modulate the patient tumour-host cell relationship.

Immunoprophylaxis and therapy of grafted rat colonic carcinoma

Two independent lines of chemically-induced colonic carcinoma, serially graftable in syngeneic rats, have been used to investigate the effects of immunoprophylaxis and immunotherapy. Rats were immunised by various procedures, including BCG, irradiated tumour grafts, and cancer cells treated by mitomycin and neuraminidase. A partial inhibition of tumour growth was observed in one of the four protocols. On the other hand, a significant enhancement of tumour growth was obtained in two other experiments.

Radiotherapy and rectal cancer

Studies utilizing preoperative radiotherapy as an adjunct to surgery are reviewed, with results indicating marked increase in survival. Results of postoperative irradiation also appear beneficial, although less extensive data are available. Irradiation for inoperable and recurrent rectal cancer has demonstrated symptomatic relief, particularly avoidance of colostomy, and can render some patients operable and resectable. Adjuvant immunotherapy after irradiation and operation is suggested for further research.

The effects of therapeutic irradiation on lymphocytes and immunity

The lymphocytotoxic effect of therapeutic irradiation may lead to immune depression. The significance of such effects is yet to be determined in many malignancies, especially in light of the persistant immune depression in many "cured" patients. The present review examines the effects of age, type of cancer, and stage of disease as well as the results of immune parameters following radiation therapy. Factors to be considered in both the analysis of present day data and in future studies are also reviewed.

Adjuvant chemotherapy with 5-fluorouracil after surgical resection of colorectal carcinoma (COG protocol 7041). A preliminary report

In a prospectively randomized study the effect of adjuvant chemotherapy with 5-FU on survival and recurrence was analyzed in 274 evaluable patients with colorectal carcinoma who either underwent a curative or a palliative resection. In the treatment group, chemotherapy consisted of the intravenous administration of 5-FU 12 mg/kg daily for four consecutive days, then 6 mg/kg/per day on alternate days to the point of toxicity or to a maximum of 5 doses, followed by 12 mg/kg/week for one year. Drug toxicity was rarely severe and consisted of nausea and vomiting, diarrhea, stomatitis, leukopenia, and thrombocytopenia in slightly more than half of all patients. There have been no drug-related deaths. Analysis of the survival curves and disease-free interval curves reveal some evidence of drug benefit in both the curative group of resections and the palliative group of resections. However, this benefit is not significant except in those treated to toxicity. The disease-free interval after curative resection is significantly longer in patients treated with 5-FU to the point of toxicity with a white blood count less than 4,000 cells/mm3. We conclude that a preliminary analysis of the Central Oncology Group data in this trial does not make a convincing case for the use of 5-FU as an adjuvant to the surgical treatment of colorectal carcinoma.